Vulnerability-Lookup

RHSA-2026:55800

Vulnerability from csaf_redhat - Published: 2026-08-17 17:26 - Updated: 2026-08-18 02:04

Summary

Red Hat Security Advisory: haproxy security update

Severity

Important

Notes

Topic: An update for haproxy is now available for Red Hat Enterprise Linux 10.0 Extended Update Support. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Details: The haproxy packages provide a reliable, high-performance network load balancer for TCP and HTTP-based applications. Security Fix(es): * haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions (CVE-2026-55204) * haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling (CVE-2026-55203) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-55203

A flaw was found in HAProxy. A malicious FastCGI (Fast Common Gateway Interface) backend can exploit an integer overflow vulnerability in the fcgi_conn structure's drl field. This occurs when specific contentLength and paddingLength values cause the drl field to wrap to zero, leading to incorrect record consumption. This desynchronizes the FCGI framing parser, potentially resulting in response smuggling, request routing errors, or memory safety issues.

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N

CWE-190 - Integer Overflow or Wraparound

Affected products

Fixed 13 products

Product	Version	Remediation
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64	—	Vendor Fix fix Workaround

Threats

Impact Important

CVE-2026-55204

A flaw was found in HAProxy. An attacker can trigger HPACK dynamic table insertions under memory pressure, leading to a null pointer dereference in the hpack_dht_insert() function. This can cause HAProxy worker processes to crash, resulting in a denial of service (DoS).

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-476 - NULL Pointer Dereference

Affected products

Fixed 13 products

Product	Version	Remediation
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x	—	Vendor Fix fix Workaround
Unresolved product id: AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64	—	Vendor Fix fix Workaround

Threats

Impact Important

References

17 references

URL	Category
https://access.redhat.com/errata/RHSA-2026:55800	self
https://access.redhat.com/security/updates/classi…	external
https://bugzilla.redhat.com/show_bug.cgi?id=2490518	external
https://bugzilla.redhat.com/show_bug.cgi?id=2490522	external
https://security.access.redhat.com/data/csaf/v2/a…	self
https://access.redhat.com/security/cve/CVE-2026-55203	self
https://bugzilla.redhat.com/show_bug.cgi?id=2490522	external
https://www.cve.org/CVERecord?id=CVE-2026-55203	external
https://nvd.nist.gov/vuln/detail/CVE-2026-55203	external
https://github.com/haproxy/haproxy/commit/5985276…	external
https://www.vulncheck.com/advisories/haproxy-inte…	external
https://access.redhat.com/security/cve/CVE-2026-55204	self
https://bugzilla.redhat.com/show_bug.cgi?id=2490518	external
https://www.cve.org/CVERecord?id=CVE-2026-55204	external
https://nvd.nist.gov/vuln/detail/CVE-2026-55204	external
https://github.com/haproxy/haproxy/commit/9a6d1fe…	external
https://www.vulncheck.com/advisories/haproxy-null…	external

JSON

To clipboard

{
  "document": {
    "aggregate_severity": {
      "namespace": "https://access.redhat.com/security/updates/classification/",
      "text": "Important"
    },
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Copyright \u00a9 Red Hat, Inc. All rights reserved.",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en",
    "notes": [
      {
        "category": "summary",
        "text": "An update for haproxy is now available for Red Hat Enterprise Linux 10.0 Extended Update Support.\n\nRed Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.",
        "title": "Topic"
      },
      {
        "category": "general",
        "text": "The haproxy packages provide a reliable, high-performance network load balancer for TCP and HTTP-based applications.\n\nSecurity Fix(es):\n\n* haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions (CVE-2026-55204)\n\n* haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling (CVE-2026-55203)\n\nFor more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.",
        "title": "Details"
      },
      {
        "category": "legal_disclaimer",
        "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.",
        "title": "Terms of Use"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "https://access.redhat.com/security/team/contact/",
      "issuing_authority": "Red Hat Product Security is responsible for vulnerability handling across all Red Hat products and services.",
      "name": "Red Hat Product Security",
      "namespace": "https://www.redhat.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "https://access.redhat.com/errata/RHSA-2026:55800",
        "url": "https://access.redhat.com/errata/RHSA-2026:55800"
      },
      {
        "category": "external",
        "summary": "https://access.redhat.com/security/updates/classification/#important",
        "url": "https://access.redhat.com/security/updates/classification/#important"
      },
      {
        "category": "external",
        "summary": "2490518",
        "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2490518"
      },
      {
        "category": "external",
        "summary": "2490522",
        "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2490522"
      },
      {
        "category": "self",
        "summary": "Canonical URL",
        "url": "https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_55800.json"
      }
    ],
    "title": "Red Hat Security Advisory: haproxy security update",
    "tracking": {
      "current_release_date": "2026-08-18T02:04:56+00:00",
      "generator": {
        "date": "2026-08-18T02:04:56+00:00",
        "engine": {
          "name": "Red Hat SDEngine",
          "version": "5.3.16"
        }
      },
      "id": "RHSA-2026:55800",
      "initial_release_date": "2026-08-17T17:26:22+00:00",
      "revision_history": [
        {
          "date": "2026-08-17T17:26:22+00:00",
          "number": "1",
          "summary": "Initial version"
        },
        {
          "date": "2026-08-17T17:26:22+00:00",
          "number": "2",
          "summary": "Last updated version"
        },
        {
          "date": "2026-08-18T02:04:56+00:00",
          "number": "3",
          "summary": "Last generated version"
        }
      ],
      "status": "final",
      "version": "3"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_name",
                "name": "Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
                "product": {
                  "name": "Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
                  "product_id": "AppStream-10.0.Z.E2S",
                  "product_identification_helper": {
                    "cpe": "cpe:/o:redhat:enterprise_linux_eus:10.0"
                  }
                }
              }
            ],
            "category": "product_family",
            "name": "Red Hat Enterprise Linux"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "haproxy-0:3.0.5-4.el10_0.3.src",
                "product": {
                  "name": "haproxy-0:3.0.5-4.el10_0.3.src",
                  "product_id": "haproxy-0:3.0.5-4.el10_0.3.src",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy@3.0.5-4.el10_0.3?arch=src"
                  }
                }
              }
            ],
            "category": "architecture",
            "name": "src"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "haproxy-0:3.0.5-4.el10_0.3.aarch64",
                "product": {
                  "name": "haproxy-0:3.0.5-4.el10_0.3.aarch64",
                  "product_id": "haproxy-0:3.0.5-4.el10_0.3.aarch64",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy@3.0.5-4.el10_0.3?arch=aarch64"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
                "product": {
                  "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
                  "product_id": "haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debugsource@3.0.5-4.el10_0.3?arch=aarch64"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
                "product": {
                  "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
                  "product_id": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debuginfo@3.0.5-4.el10_0.3?arch=aarch64"
                  }
                }
              }
            ],
            "category": "architecture",
            "name": "aarch64"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "haproxy-0:3.0.5-4.el10_0.3.ppc64le",
                "product": {
                  "name": "haproxy-0:3.0.5-4.el10_0.3.ppc64le",
                  "product_id": "haproxy-0:3.0.5-4.el10_0.3.ppc64le",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy@3.0.5-4.el10_0.3?arch=ppc64le"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
                "product": {
                  "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
                  "product_id": "haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debugsource@3.0.5-4.el10_0.3?arch=ppc64le"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
                "product": {
                  "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
                  "product_id": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debuginfo@3.0.5-4.el10_0.3?arch=ppc64le"
                  }
                }
              }
            ],
            "category": "architecture",
            "name": "ppc64le"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "haproxy-0:3.0.5-4.el10_0.3.s390x",
                "product": {
                  "name": "haproxy-0:3.0.5-4.el10_0.3.s390x",
                  "product_id": "haproxy-0:3.0.5-4.el10_0.3.s390x",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy@3.0.5-4.el10_0.3?arch=s390x"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
                "product": {
                  "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
                  "product_id": "haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debugsource@3.0.5-4.el10_0.3?arch=s390x"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
                "product": {
                  "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
                  "product_id": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debuginfo@3.0.5-4.el10_0.3?arch=s390x"
                  }
                }
              }
            ],
            "category": "architecture",
            "name": "s390x"
          },
          {
            "branches": [
              {
                "category": "product_version",
                "name": "haproxy-0:3.0.5-4.el10_0.3.x86_64",
                "product": {
                  "name": "haproxy-0:3.0.5-4.el10_0.3.x86_64",
                  "product_id": "haproxy-0:3.0.5-4.el10_0.3.x86_64",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy@3.0.5-4.el10_0.3?arch=x86_64"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64",
                "product": {
                  "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64",
                  "product_id": "haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debugsource@3.0.5-4.el10_0.3?arch=x86_64"
                  }
                }
              },
              {
                "category": "product_version",
                "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
                "product": {
                  "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
                  "product_id": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
                  "product_identification_helper": {
                    "purl": "pkg:rpm/redhat/haproxy-debuginfo@3.0.5-4.el10_0.3?arch=x86_64"
                  }
                }
              }
            ],
            "category": "architecture",
            "name": "x86_64"
          }
        ],
        "category": "vendor",
        "name": "Red Hat"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-0:3.0.5-4.el10_0.3.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64"
        },
        "product_reference": "haproxy-0:3.0.5-4.el10_0.3.aarch64",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-0:3.0.5-4.el10_0.3.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le"
        },
        "product_reference": "haproxy-0:3.0.5-4.el10_0.3.ppc64le",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-0:3.0.5-4.el10_0.3.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x"
        },
        "product_reference": "haproxy-0:3.0.5-4.el10_0.3.s390x",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-0:3.0.5-4.el10_0.3.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src"
        },
        "product_reference": "haproxy-0:3.0.5-4.el10_0.3.src",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-0:3.0.5-4.el10_0.3.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64"
        },
        "product_reference": "haproxy-0:3.0.5-4.el10_0.3.x86_64",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64"
        },
        "product_reference": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le"
        },
        "product_reference": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x"
        },
        "product_reference": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64"
        },
        "product_reference": "haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64"
        },
        "product_reference": "haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le"
        },
        "product_reference": "haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x"
        },
        "product_reference": "haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
          "product_id": "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
        },
        "product_reference": "haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64",
        "relates_to_product_reference": "AppStream-10.0.Z.E2S"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-55203",
      "cwe": {
        "id": "CWE-190",
        "name": "Integer Overflow or Wraparound"
      },
      "discovery_date": "2026-06-18T17:02:00.523729+00:00",
      "ids": [
        {
          "system_name": "Red Hat Bugzilla ID",
          "text": "2490522"
        }
      ],
      "notes": [
        {
          "category": "description",
          "text": "A flaw was found in HAProxy. A malicious FastCGI (Fast Common Gateway Interface) backend can exploit an integer overflow vulnerability in the fcgi_conn structure\u0027s drl field. This occurs when specific contentLength and paddingLength values cause the drl field to wrap to zero, leading to incorrect record consumption. This desynchronizes the FCGI framing parser, potentially resulting in response smuggling, request routing errors, or memory safety issues.",
          "title": "Vulnerability description"
        },
        {
          "category": "summary",
          "text": "haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling",
          "title": "Vulnerability summary"
        },
        {
          "category": "other",
          "text": "Conditions for Exploitation: Successful exploitation requires a specific configuration where HAProxy is actively utilizing a FastCGI backend. Crucially, an attacker must already have control over this backend server to supply the maliciously crafted responses. \n\nThis requirement significantly restricts the attack vector, as it relies on an unlikely configuration or an already compromised backend, rather than a typical remote attack initiated by a client against a default frontend server.\n\nImpact Limitations: Although the vulnerability can cause the FastCGI framing parser to desynchronize\u2014potentially leading to response smuggling, request routing errors, or memory safety issues\u2014the threat is contained entirely to environments that process traffic from untrusted or compromised backend servers.",
          "title": "Statement"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
      ],
      "product_status": {
        "fixed": [
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "Canonical URL",
          "url": "https://access.redhat.com/security/cve/CVE-2026-55203"
        },
        {
          "category": "external",
          "summary": "RHBZ#2490522",
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2490522"
        },
        {
          "category": "external",
          "summary": "https://www.cve.org/CVERecord?id=CVE-2026-55203",
          "url": "https://www.cve.org/CVERecord?id=CVE-2026-55203"
        },
        {
          "category": "external",
          "summary": "https://nvd.nist.gov/vuln/detail/CVE-2026-55203",
          "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55203"
        },
        {
          "category": "external",
          "summary": "https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd",
          "url": "https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd"
        },
        {
          "category": "external",
          "summary": "https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field",
          "url": "https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field"
        }
      ],
      "release_date": "2026-06-18T16:05:20.100000+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-08-17T17:26:22+00:00",
          "details": "For details on how to apply this update, which includes the changes described in this advisory, refer to:\n\nhttps://access.redhat.com/articles/11258",
          "product_ids": [
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
          ],
          "restart_required": {
            "category": "none"
          },
          "url": "https://access.redhat.com/errata/RHSA-2026:55800"
        },
        {
          "category": "workaround",
          "details": "To mitigate this issue, restrict access to HAProxy instances that utilize FastCGI to trusted FastCGI backends only. If FastCGI is not required, consider disabling its use in HAProxy configurations to eliminate the attack vector. Ensure that all FastCGI backends are secured and not susceptible to compromise. If the HAProxy service is reloaded or restarted after configuration changes, ensure proper validation of the new configuration.",
          "product_ids": [
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "LOW",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N",
            "version": "3.1"
          },
          "products": [
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Important"
        }
      ],
      "title": "haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling"
    },
    {
      "cve": "CVE-2026-55204",
      "cwe": {
        "id": "CWE-476",
        "name": "NULL Pointer Dereference"
      },
      "discovery_date": "2026-06-18T17:01:46.312939+00:00",
      "ids": [
        {
          "system_name": "Red Hat Bugzilla ID",
          "text": "2490518"
        }
      ],
      "notes": [
        {
          "category": "description",
          "text": "A flaw was found in HAProxy. An attacker can trigger HPACK dynamic table insertions under memory pressure, leading to a null pointer dereference in the hpack_dht_insert() function. This can cause HAProxy worker processes to crash, resulting in a denial of service (DoS).",
          "title": "Vulnerability description"
        },
        {
          "category": "summary",
          "text": "haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions",
          "title": "Vulnerability summary"
        },
        {
          "category": "other",
          "text": "This Important flaw in HAProxy can lead to a denial of service. An unauthenticated remote attacker could exploit a null pointer dereference by triggering HPACK dynamic table insertions under memory pressure, causing HAProxy worker processes to crash. This impacts the availability of services relying on HAProxy as a load balancer or proxy.",
          "title": "Statement"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
      ],
      "product_status": {
        "fixed": [
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
          "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
          "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
          "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "Canonical URL",
          "url": "https://access.redhat.com/security/cve/CVE-2026-55204"
        },
        {
          "category": "external",
          "summary": "RHBZ#2490518",
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2490518"
        },
        {
          "category": "external",
          "summary": "https://www.cve.org/CVERecord?id=CVE-2026-55204",
          "url": "https://www.cve.org/CVERecord?id=CVE-2026-55204"
        },
        {
          "category": "external",
          "summary": "https://nvd.nist.gov/vuln/detail/CVE-2026-55204",
          "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55204"
        },
        {
          "category": "external",
          "summary": "https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513",
          "url": "https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513"
        },
        {
          "category": "external",
          "summary": "https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function",
          "url": "https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function"
        }
      ],
      "release_date": "2026-06-18T16:05:52.058000+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-08-17T17:26:22+00:00",
          "details": "For details on how to apply this update, which includes the changes described in this advisory, refer to:\n\nhttps://access.redhat.com/articles/11258",
          "product_ids": [
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
          ],
          "restart_required": {
            "category": "none"
          },
          "url": "https://access.redhat.com/errata/RHSA-2026:55800"
        },
        {
          "category": "workaround",
          "details": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.",
          "product_ids": [
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "products": [
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.src",
            "AppStream-10.0.Z.E2S:haproxy-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debuginfo-0:3.0.5-4.el10_0.3.x86_64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.aarch64",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.ppc64le",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.s390x",
            "AppStream-10.0.Z.E2S:haproxy-debugsource-0:3.0.5-4.el10_0.3.x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Important"
        }
      ],
      "title": "haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions"
    }
  ]
}

CVE-2026-55203 (GCVE-0-2026-55203)

Vulnerability from cvelistv5 – Published: 2026-06-18 16:05 – Updated: 2026-07-14 21:33 X_Open Source

Title

HAProxy - Integer Overflow in FCGI Demux Record Length Field

Summary

HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.

Severity

9 (Critical)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-23 02:04 UTC

CWE

CWE-190 - Integer Overflow or Wraparound

Assigner

VulnCheck

References

2 references

URL	Tags
https://github.com/haproxy/haproxy/commit/5985276…	patch
https://www.vulncheck.com/advisories/haproxy-inte…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
haproxy	haproxy	Affected: 0 , ≤ 3.4.0 (semver) Unaffected: 5985276735777634d8c85f1d73bb7764aab0d6dd (git) cpe:2.3:a:haproxy:aloha::::::::

Date Public

2026-06-16 00:00

Credits

Tristan Madani (@TristanInSec)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55203",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-23T02:04:34.549032Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-23T02:04:44.933Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:github/haproxy/haproxy",
          "product": "haproxy",
          "repo": "https://github.com/haproxy/haproxy",
          "vendor": "haproxy",
          "versions": [
            {
              "lessThanOrEqual": "3.4.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5985276735777634d8c85f1d73bb7764aab0d6dd",
              "versionType": "git"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:haproxy:aloha:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "3.4.0",
                  "vulnerable": true
                }
              ],
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Tristan Madani (@TristanInSec)"
        }
      ],
      "datePublic": "2026-06-16T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure\u0027s drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9,
            "baseSeverity": "CRITICAL",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "LOW",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "LOW",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-190",
              "description": "Integer Overflow or Wraparound",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-14T21:33:57.207Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "Patch Commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field"
        }
      ],
      "tags": [
        "x_open-source"
      ],
      "title": "HAProxy - Integer Overflow in FCGI Demux Record Length Field",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-55203",
    "datePublished": "2026-06-18T16:05:20.100Z",
    "dateReserved": "2026-06-16T15:53:37.764Z",
    "dateUpdated": "2026-07-14T21:33:57.207Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

CVE-2026-55204 (GCVE-0-2026-55204)

Vulnerability from cvelistv5 – Published: 2026-06-18 16:05 – Updated: 2026-07-14 21:33 X_Open Source

Title

HAProxy - NULL Pointer Dereference in hpack_dht_insert Function

Summary

HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-18 17:26 UTC

CWE

CWE-476 - NULL Pointer Dereference

Assigner

VulnCheck

References

2 references

URL	Tags
https://github.com/haproxy/haproxy/commit/9a6d1fe…	patch
https://www.vulncheck.com/advisories/haproxy-null…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
haproxy	haproxy	Affected: 0 , ≤ 3.4.0 (semver) Unaffected: 9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513 (git) cpe:2.3:a:haproxy:aloha::::::::

Date Public

2026-06-16 00:00

Credits

Tristan Madani (@TristanInSec)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55204",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-18T17:26:27.738915Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-18T17:26:38.498Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:github/haproxy/haproxy",
          "product": "haproxy",
          "repo": "https://github.com/haproxy/haproxy",
          "vendor": "haproxy",
          "versions": [
            {
              "lessThanOrEqual": "3.4.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513",
              "versionType": "git"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:haproxy:aloha:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "3.4.0",
                  "vulnerable": true
                }
              ],
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Tristan Madani (@TristanInSec)"
        }
      ],
      "datePublic": "2026-06-16T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "HAProxy through  3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-476",
              "description": "NULL Pointer Dereference",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-14T21:33:57.879Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "Patch Commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function"
        }
      ],
      "tags": [
        "x_open-source"
      ],
      "title": "HAProxy - NULL Pointer Dereference in hpack_dht_insert Function",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-55204",
    "datePublished": "2026-06-18T16:05:52.058Z",
    "dateReserved": "2026-06-16T15:53:37.765Z",
    "dateUpdated": "2026-07-14T21:33:57.879Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

RHSA-2026:55800

CVE-2026-55203 (GCVE-0-2026-55203)

CVE-2026-55204 (GCVE-0-2026-55204)

Tags

Sightings

Nomenclature