CVE-2026-75595

Description

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.

References

https://github.com/netty/netty/security/advisories/GHSA-c4c3-7fpv-j4q5

https://github.com/netty/netty/releases/tag/netty-4.2.17.Final

https://github.com/netty/netty/releases/tag/netty-4.1.137.Final

https://github.com/netty/netty/pull/17217

https://github.com/netty/netty/pull/17213

https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961

https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-63095

Details

Source: Mitre, NVD

Named Vulnerability: GHSA-c4c3-7fpv-j4q5

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS