CVE-2026-45416 — Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes

Affected: netty, Red Hat Cryostat 4 on RHEL 9, Red Hat AMQ Broker 7.13.6, Red Hat AMQ Broker 7.14.1, Red Hat Build of Apache Camel 3.33 for Quarkus 3.33.2.SP1, Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16, Red Hat build of Quarkus 3.27.4.SP1, Red Hat build of Quarkus 3.33.2.SP1, Red Hat Data Grid 8.6.2, Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7 and 26 more

Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, SslClientHelloHandler.decode() reads the 24-bit TLS handshake length and, when the ClientHello does not fit in the first record, eagerly allocates `ctx.alloc().buffer(handshakeLength)` (line 161). The guard at line 140 is `handshakeLength > maxClientHelloLength && maxClientHelloLength != 0`, and the commonly-used SniHandler/AbstractSniHandler constructors (SniHandler(Mapping), SniHandler(AsyncMapping), AbstractSniHandler()) pass maxClientHelloLength=0 and handshakeTimeoutMillis=0, so the length guard is disabled and no timeout is scheduled. A 16 MiB request exceeds the default pooled chunk size and becomes a huge/unpooled allocation performed immediately. The buffer is retained in the handler until the channel closes. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

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CVE-2026-45416 — Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes