CVE-2026-75595

Summary

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Fina and 4.2.17.Final, io.netty.handler.ssl.SslClientHelloHandler#decode checks the wrong offset before reading the four-byte TLS handshake header, so a ClientHello whose handshake header spans records can cause an IndexOutOfBoundsException and invoke select(ctx, null). This selects the default SslContext instead of the SNI-specific context. In deployments where per-SNI clientAuth=REQUIRE is the sole mutual TLS gate, the default SslContext uses clientAuth=NONE or clientAuth=OPTIONAL, and no application-layer certificate verification exists, an unauthenticated remote attacker can bypass the protected route's mutual TLS requirement. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

Affected Software

VendorProductVersion RangeStatus
nettynetty< 4.1.137.Finalaffected
nettynetty>= 4.2.0.Final, < 4.2.17.Finalaffected

Weaknesses

  • CWE-754: CWE-754: Improper Check for Unusual or Exceptional Conditions

References