TCP Fast Open Misconfiguration in Linux Kernel Software

CVE-2026-74696

What is CVE-2026-74696?

A significant flaw in the Linux kernel's management of TCP Fast Open leads to inaccurate accounting of pending connection requests. This issue arises during the reuse of socket listeners when transitioning between different processes, allowing more Fast Open requests to pass through than originally allowed. Specifically, the misaligned charge and uncharge mechanism during listener migration results in a negative queue length for the new listener, which bypasses its configured limits. Addressing this issue involves proper charging during the migration phase to maintain accurate request handling and secure network performance.

References