Vulnerability-Lookup

UBUNTU-CVE-2026-56821 (CVE-2026-56821)

Vulnerability from osv_ubuntu – Published: 2026-07-29 00:16 – Updated: 2026-09-10 14:29 – Source website

Details

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Severity

7.4 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-56821	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-56821	REPORT
	https://github.com/netty/netty/security/advisorie…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:3.2.6.Final-2",
        "1:3.2.6.Final-2+deb8u2build0.14.04.1~esm1",
        "1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:4.0.34-1ubuntu0.1~esm5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:4.0.34-1ubuntu0.1~esm5?arch=source\u0026distro=esm-apps-legacy/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:3.2.6.Final-2",
        "1:4.0.32-1",
        "1:4.0.33-1",
        "1:4.0.34-1",
        "1:4.0.34-1ubuntu0.1~esm1",
        "1:4.0.34-1ubuntu0.1~esm2",
        "1:4.0.34-1ubuntu0.1~esm3",
        "1:4.0.34-1ubuntu0.1~esm4",
        "1:4.0.34-1ubuntu0.1~esm5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:4.1.7-4ubuntu0.1+esm7"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:4.1.7-4ubuntu0.1+esm7?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:4.1.7-4",
        "1:4.1.7-4ubuntu0.1~esm1",
        "1:4.1.7-4ubuntu0.1",
        "1:4.1.7-4ubuntu0.1+esm1",
        "1:4.1.7-4ubuntu0.1+esm2",
        "1:4.1.7-4ubuntu0.1+esm3",
        "1:4.1.7-4ubuntu0.1+esm4",
        "1:4.1.7-4ubuntu0.1+esm5",
        "1:4.1.7-4ubuntu0.1+esm6",
        "1:4.1.7-4ubuntu0.1+esm7"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:4.1.45-1ubuntu0.1~esm7"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:4.1.45-1ubuntu0.1~esm7?arch=source\u0026distro=esm-apps/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:4.1.33-1",
        "1:4.1.33-2",
        "1:4.1.33-3",
        "1:4.1.45-1",
        "1:4.1.45-1ubuntu0.1~esm1",
        "1:4.1.45-1ubuntu0.1~esm2",
        "1:4.1.45-1ubuntu0.1~esm3",
        "1:4.1.45-1ubuntu0.1~esm4",
        "1:4.1.45-1ubuntu0.1~esm6",
        "1:4.1.45-1ubuntu0.1~esm7"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:4.1.48-4+deb11u2ubuntu0.2+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:4.1.48-4+deb11u2ubuntu0.2+esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:4.1.48-4",
        "1:4.1.48-4+deb11u1build0.22.04.1",
        "1:4.1.48-4+deb11u2build0.22.04.1",
        "1:4.1.48-4+deb11u2ubuntu0.1~esm1",
        "1:4.1.48-4+deb11u2ubuntu0.1~esm2",
        "1:4.1.48-4+deb11u2ubuntu0.1",
        "1:4.1.48-4+deb11u2ubuntu0.1+esm1",
        "1:4.1.48-4+deb11u2ubuntu0.1+esm3",
        "1:4.1.48-4+deb11u2ubuntu0.2",
        "1:4.1.48-4+deb11u2ubuntu0.2+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:4.1.48-9ubuntu0.2+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:4.1.48-9ubuntu0.2+esm2?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:4.1.48-7",
        "1:4.1.48-8",
        "1:4.1.48-9",
        "1:4.1.48-9ubuntu0.1~esm1",
        "1:4.1.48-9ubuntu0.1~esm2",
        "1:4.1.48-9ubuntu0.1",
        "1:4.1.48-9ubuntu0.1+esm1",
        "1:4.1.48-9ubuntu0.1+esm3",
        "1:4.1.48-9ubuntu0.2",
        "1:4.1.48-9ubuntu0.2+esm1",
        "1:4.1.48-9ubuntu0.2+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libnetty-buffer-java",
            "binary_version": "1:4.1.48-16ubuntu0.1~esm2"
          },
          {
            "binary_name": "libnetty-common-java",
            "binary_version": "1:4.1.48-16ubuntu0.1~esm2"
          },
          {
            "binary_name": "libnetty-java",
            "binary_version": "1:4.1.48-16ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:26.04:LTS",
        "name": "netty",
        "purl": "pkg:deb/ubuntu/netty@1:4.1.48-16ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:4.1.48-10",
        "1:4.1.48-11",
        "1:4.1.48-12",
        "1:4.1.48-13",
        "1:4.1.48-14",
        "1:4.1.48-16",
        "1:4.1.48-16ubuntu0.1~esm2"
      ]
    }
  ],
  "aliases": [],
  "details": "Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.",
  "id": "UBUNTU-CVE-2026-56821",
  "modified": "2026-09-10T14:29:54Z",
  "published": "2026-07-29T00:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-56821"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-56821"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-56821"
  ]
}

CVE-2026-56821 (GCVE-0-2026-56821)

Vulnerability from cvelistv5 – Published: 2026-07-28 23:07 – Updated: 2026-07-31 16:12

Title

Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator

Summary

Severity

7.4 (High)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-30 03:55 UTC

CWE

CWE-299 - Improper Check for Certificate Revocation

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/netty/netty/security/advisorie…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
netty	netty	Affected: < 4.1.136.Final Affected: >= 4.2.0.Final, < 4.2.16.Final

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-56821",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-30T03:55:19.093244Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-31T16:12:56.878Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "netty",
          "vendor": "netty",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.1.136.Final"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.2.0.Final, \u003c 4.2.16.Final"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-299",
              "description": "CWE-299: Improper Check for Certificate Revocation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-29T17:32:19.753Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr"
        }
      ],
      "source": {
        "advisory": "GHSA-g7hg-vrcf-mvmr",
        "discovery": "UNKNOWN"
      },
      "title": "Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-56821",
    "datePublished": "2026-07-28T23:07:13.616Z",
    "dateReserved": "2026-06-23T14:55:09.116Z",
    "dateUpdated": "2026-07-31T16:12:56.878Z",
    "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.
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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.

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.
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UBUNTU-CVE-2026-56821 (CVE-2026-56821)

CVE-2026-56821 (GCVE-0-2026-56821)

Tags

Sightings

Nomenclature

Related by attack behaviour