Malformed Packet Vulnerability in Linux Kernel's sch_cake TCP Header Filtering

CVE-2026-74704

What is CVE-2026-74704?

The sch_cake modem in the Linux kernel has a flaw in its ACK filter that can be triggered by malformed IP headers. While designed to filter duplicate ACKs during backlogged network flows, the existing code contains a redundant WARN_ON(1) statement. This can lead to excessive warnings being logged in dmesg, or even cause system panic if certain configurations are set. The code has been optimized to skip offending packets already, so the removal of the WARN_ON will prevent unnecessary log overflow and system instability.

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