Netty: SNI handler pre-allocates up to 16 MiB from nine attacker bytes

高 7.5CVE-2026-45416 · GHSA-x4gw-5cx5-pgmh · 12/06/2026 公開 · 18/09/2026 更新

要点

CVE-2026-45416 は io.netty:netty-handler, netty (netty) に影響する深刻度「高」 (CVSS 7.5) の脆弱性です。
今後30日間に悪用される確率（EPSS）：0.92%（全脆弱性の 60.3% より高い）。
対処：4.2.15.Final, 4.1.135.Final, 4.2.15, 4.1.135 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
io.netty:netty-handler Maven	`≥ 4.2.0.Final, < 4.2.15.Final< 4.1.135.Final`	`4.2.15.Final4.1.135.Final`
netty netty	`≥ 4.2.0, < 4.2.15< 4.1.135`	`4.2.154.1.135`

概要

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.

NVD の説明

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.