Vulnerability-Lookup

ubuntu-cve-2026-31842

Vulnerability from osv_ubuntu

Published

2026-04-07 12:16

Modified

2026-05-20 15:27

Summary

Details

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass.

Severity

7.5 (High)


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

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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-31842	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-31842	REPORT
	https://datatracker.ietf.org/doc/html/rfc7230	REPORT
	https://github.com/tinyproxy/tinyproxy	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.8.3-3ubuntu14.04.1~esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.8.3-3ubuntu14.04.1~esm3?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.3-3ubuntu1",
        "1.8.3-3ubuntu14.04.1~esm1",
        "1.8.3-3ubuntu14.04.1~esm2",
        "1.8.3-3ubuntu14.04.1~esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.8.3-3ubuntu16.04.1~esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.8.3-3ubuntu16.04.1~esm3?arch=source\u0026distro=esm-apps/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.3-3ubuntu1",
        "1.8.3-3ubuntu16.04.1~esm1",
        "1.8.3-3ubuntu16.04.1~esm2",
        "1.8.3-3ubuntu16.04.1~esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.8.4-5ubuntu0.1~esm3"
          },
          {
            "binary_name": "tinyproxy-bin",
            "binary_version": "1.8.4-5ubuntu0.1~esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.8.4-5ubuntu0.1~esm3?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.4-2",
        "1.8.4-3",
        "1.8.4-5",
        "1.8.4-5ubuntu0.1~esm1",
        "1.8.4-5ubuntu0.1~esm2",
        "1.8.4-5ubuntu0.1~esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.10.0-4ubuntu0.2"
          },
          {
            "binary_name": "tinyproxy-bin",
            "binary_version": "1.10.0-4ubuntu0.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.10.0-4ubuntu0.2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10.0-2",
        "1.10.0-4",
        "1.10.0-4ubuntu0.1",
        "1.10.0-4ubuntu0.2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.11.0-1ubuntu0.1~esm2"
          },
          {
            "binary_name": "tinyproxy-bin",
            "binary_version": "1.11.0-1ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.11.0-1ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.10.0-5",
        "1.11.0-1",
        "1.11.0-1ubuntu0.1~esm1",
        "1.11.0-1ubuntu0.1~esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.11.1-3ubuntu0.1"
          },
          {
            "binary_name": "tinyproxy-bin",
            "binary_version": "1.11.1-3ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.11.1-3ubuntu0.1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.1-2.1",
        "1.11.1-3",
        "1.11.1-3ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.11.2-1"
          },
          {
            "binary_name": "tinyproxy-bin",
            "binary_version": "1.11.2-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.11.2-1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.2-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "tinyproxy",
            "binary_version": "1.11.3-1"
          },
          {
            "binary_name": "tinyproxy-bin",
            "binary_version": "1.11.3-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "tinyproxy",
        "purl": "pkg:deb/ubuntu/tinyproxy@1.11.3-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.11.2-1",
        "1.11.2-1build1",
        "1.11.3-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against \"chunked\", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass.",
  "id": "UBUNTU-CVE-2026-31842",
  "modified": "2026-05-20T15:27:20Z",
  "published": "2026-04-07T12:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-31842"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-31842"
    },
    {
      "type": "REPORT",
      "url": "https://datatracker.ietf.org/doc/html/rfc7230"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/tinyproxy/tinyproxy"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-31842"
  ]
}

CVE-2026-31842 (GCVE-0-2026-31842)

Vulnerability from cvelistv5 – Published: 2026-04-07 11:17 – Updated: 2026-04-07 16:30

Title

Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling

Summary

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: poc Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Assigner

TuranSec

References

3 references

URL	Tags
https://github.com/tinyproxy/tinyproxy/issues/604	issue-trackingtechnical-descriptionthird-party-advisory
https://github.com/tinyproxy/tinyproxy	product
https://datatracker.ietf.org/doc/html/rfc7230	technical-description

Impacted products

1 product

Vendor	Product	Version
Tinyproxy Project	Tinyproxy	Affected: 0 , ≤ 1.11.3 (custom)

Credits

Muxammadiyev G'iyosiddin

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
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            "other": {
              "content": {
                "id": "CVE-2026-31842",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-07T16:30:26.482367Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
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        "providerMetadata": {
          "dateUpdated": "2026-04-07T16:30:44.774Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/tinyproxy/tinyproxy",
          "defaultStatus": "unaffected",
          "platforms": [
            "all"
          ],
          "product": "Tinyproxy",
          "vendor": "Tinyproxy Project",
          "versions": [
            {
              "lessThanOrEqual": "1.11.3",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
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          "lang": "en",
          "type": "finder",
          "value": "Muxammadiyev G\u0027iyosiddin"
        }
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        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eTinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against \"chunked\", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass.\u003c/p\u003e"
            }
          ],
          "value": "Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against \"chunked\", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass."
        }
      ],
      "impacts": [
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          "descriptions": [
            {
              "lang": "en",
              "value": "An unauthenticated remote attacker can trigger HTTP request parsing desynchronization using a mixed-case Transfer-Encoding header (e.g., \u0027Chunked\u0027), leading to backend connection hangs and denial of service. In certain deployments, request-body inspection and filtering mechanisms relying on Tinyproxy may also be bypassed."
            }
          ]
        }
      ],
      "metrics": [
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          "cvssV4_0": {
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            "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"
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          "scenarios": [
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              "value": "GENERAL"
            }
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        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444 Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
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          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-07T11:17:33.621Z",
        "orgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
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      },
      "references": [
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          "tags": [
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            "technical-description",
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          "url": "https://github.com/tinyproxy/tinyproxy/issues/604"
        },
        {
          "name": "Tinyproxy upstream project",
          "tags": [
            "product"
          ],
          "url": "https://github.com/tinyproxy/tinyproxy"
        },
        {
          "name": "RFC 7230: transfer-coding names are case-insensitive",
          "tags": [
            "technical-description"
          ],
          "url": "https://datatracker.ietf.org/doc/html/rfc7230"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
    "assignerShortName": "TuranSec",
    "cveId": "CVE-2026-31842",
    "datePublished": "2026-04-07T11:17:33.621Z",
    "dateReserved": "2026-03-09T18:20:23.398Z",
    "dateUpdated": "2026-04-07T16:30:44.774Z",
    "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.

Action not permitted

ubuntu-cve-2026-31842

Vulnerability from osv_ubuntu

CVE-2026-31842 (GCVE-0-2026-31842)

Tags

Sightings

Nomenclature