CVE-2026-75596Netty: Fragmented ClientHello records trigger quadratic pre-handshake reassembly in default SNI parsing

Beschreibung

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, the default io.netty.handler.ssl.SniHandler constructors use the pre-handshake ClientHello aggregation path in handler/src/main/java/io/netty/handler/ssl/SslClientHelloHandler.java at io.netty.handler.ssl.SslClientHelloHandler#decode, where handshakeBuffer.clear() and writeBytes() recopy all previously received body bytes for every additional TLS record. An unauthenticated remote peer can advertise a large ClientHello and deliver its body in thousands of tiny records, causing quadratic CPU work on the event loop before the TLS handshake completes and degrading TLS handling for other clients. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

Daten: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Wiedergegeben wie in der Quelle, auf Englisch.

Betroffene Produkte und Versionen

Referenzen und Patches

• https://github.com/netty/netty/security/advisories/GHSA-fccg-mwvh-qqg4 Vendor Advisory
• https://github.com/netty/netty/pull/17213 Issue TrackingPatch
• https://github.com/netty/netty/pull/17217 Issue TrackingPatch
• https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7 Patch
• https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961 Patch
• https://github.com/netty/netty/releases/tag/netty-4.1.137.Final Release Notes
• https://github.com/netty/netty/releases/tag/netty-4.2.17.Final Release Notes