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CVE-2026-56821

HIGH
7.4
CVSS 3.1
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 Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response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.

Metadata

CVE ID
CVE-2026-56821
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-06-23 14:55 UTC
Published
2026-07-28 23:07 UTC
Last updated
2026-07-28 23:07 UTC
Primary CWE
CWE-299
CWE-299: Improper Check for Certificate Revocation
Vendor / Product
netty / netty
Sources
cve.org  ·  NVD

Severity & Metrics

7.4 HIGH CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected products (1)
VendorProductPlatformVersions
netty netty — < 4.1.136.Final, >=4.2.0.Final, < 4.2.16.Final
Weakness (CWE)
CWESourceDescription
CWE-299 cna CWE-299: Improper Check for Certificate Revocation
CVSS scores (1)
ScoreSeverityVersionSourceVector
7.4 HIGH 3.1 cna CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
References (1)
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