Improper Certificate Validation Affecting io.netty:netty-codec-classes-quic package, versions [4.2.11.Final,4.2.18.Final)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JAVA-IONETTY-20154418
- published27 Sept 2026
- disclosed26 Sept 2026
- creditRex Liu
Introduced: 26 Sep 2026
NewCVE-2026-100665 (opens in a new tab)How to fix?
Upgrade io.netty:netty-codec-classes-quic to version 4.2.18.Final or higher.
Overview
Affected versions of this package are vulnerable to Improper Certificate Validation in the verify(...) method of BoringSSLCertificateVerifyCallback, which for a plain X509TrustManager invokes only the two-argument checkServerTrusted(chain, authType) overload, dropping the QuicheQuicSslEngine that carries the peer host and SSLParameters so the configured HTTPS endpoint identification is never enforced. An attacker can impersonate the intended server by answering the connection with a certificate chain that the application's trust manager accepts but that is not valid for the requested peer host, which the QUIC client then accepts. This requires a client built through QuicSslContextBuilder.forClient() with a plain X509TrustManager supplied rather than an X509ExtendedTrustManager, and the endpoint identification algorithm set to HTTPS.
Workaround
This vulnerability can be avoided by supplying an X509ExtendedTrustManager instead of a plain X509TrustManager, so the verification path retains the engine carrying the peer host and applies the configured endpoint identification.
Note: This is a bypass of the fix for the vulnerability described in CVE-2026-50010.