{"id":"CVE-2026-75595","aliases":[],"url":"https://o3.security/vulnerability/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…","details":"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.","published":"2026-08-19T21:17:37.563","modified":"2026-08-19T21:17:37.563","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7","label":"netty/netty@1b5abc6"},"references":[{"type":"WEB","url":"https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7"},{"type":"WEB","url":"https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961"},{"type":"WEB","url":"https://github.com/netty/netty/pull/17213"},{"type":"WEB","url":"https://github.com/netty/netty/pull/17217"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.1.137.Final"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.17.Final"},{"type":"WEB","url":"https://github.com/netty/netty/security/advisories/GHSA-c4c3-7fpv-j4q5"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-08-19T21:17:37.563"}}