GHSA-x4gw-5cx5-pgmh — Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes

Affected: Maven: io.netty:netty-handler

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.

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GHSA-x4gw-5cx5-pgmh — Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes