Security Bulletin:Netty Versions 4.2.0.Final-4.2.16.Final, 4.1.136.Final: TLS Hostname Verification Disabled

Summary Netty io.netty:netty-handler versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable 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...

Improper Certificate Validation

Netty is vulnerable to Improper Certificate Validation. The vulnerability is due to disabled TLS hostname verification in the SslProvider.OPENSSL client path under specific configurations, which allows a man-in-the-middle attacker to present a certificate issued for a different hostname and...

io.netty/netty-handler: Netty: TLS hostname verification bypass via OpenSSL client path misconfiguration

A flaw was found in Netty io.netty:netty-handler. When using the SslProvider.OPENSSL client path with a plain X509TrustManager and without Unsafe-based trust-manager wrapping Java 25+, TLS hostname verification is disabled. This misconfiguration allows a man-in-the-middle attacker to present a...

io.netty/netty-handler: Netty: TLS hostname verification bypass via OpenSSL client path misconfiguration

A flaw was found in Netty io.netty:netty-handler. When using the SslProvider.OPENSSL client path with a plain X509TrustManager and without Unsafe-based trust-manager wrapping Java 25+, TLS hostname verification is disabled. This misconfiguration allows a man-in-the-middle attacker to present a...

io.netty/netty-handler: Netty: TLS hostname verification bypass via OpenSSL client path misconfiguration

A flaw was found in Netty io.netty:netty-handler. When using the SslProvider.OPENSSL client path with a plain X509TrustManager and without Unsafe-based trust-manager wrapping Java 25+, TLS hostname verification is disabled. This misconfiguration allows a man-in-the-middle attacker to present a...

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

Netty io.netty:netty-handler versions from 4.2.0.Final through 4.2.16.Final and versions through 4.1.136.Final disable 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...