CVE-2026-45416
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk37th percentile - higher than 37% of all known CVEs
Summary
A vulnerability in the Netty library allows an attacker to trigger a large memory allocation by sending a crafted ClientHello message in TLS handshake. The buffer is allocated immediately and retained until the connection closes, potentially leading to resource exhaustion.
Risk Assessment
The risk is a Denial of Service (DoS) attack where a large ClientHello packet can exhaust server memory, causing application unavailability.
Recommendation
Upgrade Netty to version 4.1.135.Final or 4.2.15.Final immediately to mitigate this vulnerability.
Original NVD description (English source)
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.