Bug 2521452 (CVE-2026-74704) - CVE-2026-74704 kernel: net/sched: sch_cake: drop WARN_ON(1) for malformed packets in ACK filter
Summary: CVE-2026-74704 kernel: net/sched: sch_cake: drop WARN_ON(1) for malformed pac...
Keywords:
Status: NEW
Alias: CVE-2026-74704
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-22 15:46 UTC by OSIDB Bzimport
Modified: 2026-08-24 17:38 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-08-22 15:46:18 UTC
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.


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