High 7.4Published Jul 21, 2026

CVE-2026-56820Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks

Updated under an hour ago (Oct 27, 2026, 4:30 PM ET)

This data is behind schedule: last updated Oct 27, 2026, 4:30 PM ET. We are working on it.Behind: CVE records (cvelistV5).

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Every CVE for netty

Exploited in the last 30 days

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and prior to 4.1.135.Final, `OcspClient` does not validate that the `CertificateID` in an OCSP response matches the requested `CertificateID`, which can lead to replay attack. `OcspClient.validateResponse` accepts a legitimately signed `GOOD` status response for an unrelated certificate issued by the same CA, allowing bypass of revocation checks for another certificate. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

CVSS: 7.4 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-295
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 24, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

netty netty netty:netty (from the name)	from 4.2.0.Final, < 4.2.16.Final; before 4.1.136.Final	CNA record
netty netty netty:netty	before 4.1.136; from 4.2.0 before 4.2.16	NVD

References

References

https://github.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg	x-refsource-confirm, exploit, vendor-advisory
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b	x-refsource-misc, patch
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6	x-refsource-misc, patch
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final	x-refsource-misc, release-notes
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.