CVE-2026-62243: Improper Validation of Certificate with Host Mismatch

August 22, 2026 (updated October 8, 2026)

Netty disables TLS hostname verification on the SslProvider.OPENSSL client path when a plain (non-extended) X509TrustManager is used and Unsafe-based trust-manager wrapping is unavailable (Java 25+). In this configuration the OpenSSL client does not perform hostname verification, allowing a man-in-the-middle attacker to present a certificate issued for a different hostname that is accepted without validation.

References

github.com/netty/netty/security/advisories/GHSA-p85m-gvr3-788c
nvd.nist.gov/vuln/detail/CVE-2026-62243

Code Behaviors & Features

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