CVE-2026-75595
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 4.0
- 9.1
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 24% of CVEs (scores of 2026-10-25)
- CWE
- CWE-754
- Published
- Modified
- Record from
- the NVD, synced
Affected
- netty:netty
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-c4c3-7fpv-j4q5 | Maven | io.netty:netty-handler | >=4.2.0.Final <4.2.17.Final | 4.2.17.Final |
| GHSA-c4c3-7fpv-j4q5 | Maven | io.netty:netty-handler | <4.1.137.Final | 4.1.137.Final |
References
- https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7
- https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961
- https://github.com/netty/netty/pull/17213
- https://github.com/netty/netty/pull/17217
- https://github.com/netty/netty/releases/tag/netty-4.1.137.Final