What’s Vulnerable › Vulnerabilities

CVE-2026-74704: net/sched: sch_cake: drop WARN_ON(1) for malformed packets in ACK filter

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-22 · updated 2026-10-16

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_cake: drop WARN_ON(1) for malformed packets in ACK filter The sch_cake ACK filter parses packets to find the TCP header and filter duplicated ACKs if the flow is backlogged. The parsing code contains a WARN_ON(1) which can be triggered by a malformed IP header in certain cases. Depending on the system configuration, this leads either to either spamming dmesg with warnings, or a panic if panic_on_warn is set. The code already correctly skips the offending packet in the branch that triggers the warning, so the WARN_ON itself doesn't really serve any purpose. So just drop it altogether to avoid the inconvenient side effects.

Affected products

• Linux kernel: 4.19 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0c4882bff34558d8d53fb04c3e96da5c327c7dc8
• https://git.kernel.org/stable/c/2504a76e5c0694e14e15562730e1339f2d9f9458
• https://git.kernel.org/stable/c/2a33516f9ef59ad11844d4fc152f889449b5daf3
• https://git.kernel.org/stable/c/a1ae353d8355407c1bea971d1c1af5e7f242bb7d
• https://git.kernel.org/stable/c/a4b52612004a5639c4bfc30ba93ba414b8326e2a
• https://git.kernel.org/stable/c/ae1b2f8e21a41e7c7e75511bea0c4ccc59ec1bd3
• https://git.kernel.org/stable/c/c1693b7844a6c06d31a565e5a494948034dfd235
• https://git.kernel.org/stable/c/cd2f1d9fe8a507c2dc86ad326fe221f121c47734

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