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Security Advisories

CVE-2026-56821

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-56821

Severity

7.4

High

CVSS V3

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Summary

Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator

Description

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 Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response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.

References

  • https://nvd.nist.gov/vuln/detail/CVE-2026-56821
  • https://github.com/advisories/GHSA-g7hg-vrcf-mvmr
  • https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56821.json
  • https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr

Affected packages

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