io.netty/netty-handler: Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext

A flaw was found in Netty, an asynchronous, event-driven network application framework. An unauthenticated remote attacker can exploit fragmented Transport Layer Security TLS ClientHello messages to bypass the Server Name Indication SNI routing mechanism. This forces a fallback to a less secure...

Netty: SNI Routing Bypass via Fragmented TLS ClientHello Causing Fallback to Default SslContext

Summary A fragmented TLS ClientHello whose handshake header spans multiple records makes Netty silently fall back to the default SslContext; where per-SNI selection is the sole mTLS gate, an unauthenticated attacker can bypass the route's mTLS requirement. Details In...

CVE-2026-75595

Netty (asynchronous, event-driven network framework) is affected by an SNI routing bypass in io.netty.handler.ssl.SslClientHelloHandler#decode . The method checks the wrong offset before reading the four-byte TLS handshake header, so a ClientHello whose handshake header spans records triggers an ...