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Vulnerability record · CVE-2026-100665 · published 26 September 2026

CVE-2026-100665: Improper certificate validation vulnerability

Netty versions from 4.2.11.Final before 4.2.18.Final contain an incomplete hostname verification fix in the QUIC certificate verification path when using a plain X509TrustManager. The BoringSSLCertificateVerifyCallback discards the SSLEngine for plain trust managers, preventing endpoint identification from running even when HTTPS verification is configured. Attackers on the network path can present a certificate chain for the wrong hostname that the plain trust manager accepts, bypassing hostname authentication for QUIC clients.

8.7 CVSS 4.0 High CWE-295 · Improper certificate validation Received
8.7CVSS 4.0 base score
—EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
27 Sep 2026Last modified by NVD

Description

Netty versions from 4.2.11.Final before 4.2.18.Final contain an incomplete hostname verification fix in the QUIC certificate verification path when using a plain X509TrustManager. The BoringSSLCertificateVerifyCallback discards the SSLEngine for plain trust managers, preventing endpoint identification from running even when HTTPS verification is configured. Attackers on the network path can present a certificate chain for the wrong hostname that the plain trust manager accepts, bypassing hostname authentication for QUIC clients.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/netty/netty/commit/09e72c4fd8007277121ed48db63a124b112b96fe
https://github.com/netty/netty/commit/994e887ed9
https://github.com/netty/netty/security/advisories/GHSA-mj35-3qqm-q387
https://www.vulncheck.com/advisories/netty-4.2.11-through-4.2.17-quic-hostname-verification-bypass

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Source: NIST National Vulnerability Database (record CVE-2026-100665), CISA KEV, FIRST EPSS. This page is refreshed as NVD updates the record.