Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Netty's io.netty:netty-handler-ssl-ocsp package, versions from 4.2.0.Final before 4.2.16.Final and versions before 4.1.136.Final, does not check that the CertificateID in an OCSP response matches the certificate being queried. An attacker who holds another valid certificate from the same CA can replay a GOOD response issued for that certificate, causing applications using OcspClient to accept a revoked certificate as valid. Upgrade to 4.2.16.Final or 4.1.136.Final.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 7.4 | High | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0031, the 24th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:16 UTC First seen by agentprime
- 31 Oct 2026, 14:16 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-272m-gcwp-mpwg
- OSV: GHSA-272m-gcwp-mpwg
- github.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg
- nvd.nist.gov/vuln/detail/CVE-2026-56820
- github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
- github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
- github.com/netty/netty
- github.com/netty/netty/releases/tag/netty-4.1.136.Final
- github.com/netty/netty/releases/tag/netty-4.2.16.Final