Concurrency Issue in Linux Kernel's Netfilter Component for SYNPROXY

CVE-2026-53269

What is CVE-2026-53269?

A race condition has been identified within the Linux Kernel's Netfilter component relating to SYNPROXY. This issue arises when the synproxy infrastructure registers netfilter hooks concurrently during the initial addition of iptables targets or nftables expressions. The introduction of a mutex serves to serialize the reference count control, thereby preventing conflicts that could compromise system integrity. While implementing a per namespace mutex option exists, it is not deemed necessary for targets or expressions such as SYNPROXY.

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