CVE-2026-75595
criticalNetty is an asynchronous, event-driven network application framework.
Vendor / product: Netty — netty
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Affected products
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
References
- https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7 security-advisories@github.com
- https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961 security-advisories@github.com
- https://github.com/netty/netty/pull/17213 security-advisories@github.com
- https://github.com/netty/netty/pull/17217 security-advisories@github.com
- https://github.com/netty/netty/releases/tag/netty-4.1.137.Final security-advisories@github.com
- https://github.com/netty/netty/releases/tag/netty-4.2.17.Final security-advisories@github.com
- https://github.com/netty/netty/security/advisories/GHSA-c4c3-7fpv-j4q5 security-advisories@github.com