What’s Vulnerable › Vulnerabilities

CVE-2025-37798: codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog()

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-05-02 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog() After making all ->qlen_notify() callbacks idempotent, now it is safe to remove the check of qlen!=0 from both fq_codel_dequeue() and codel_qdisc_dequeue().

Affected products

• Debian Linux: 11.0
• Linux kernel: from 3.5 before 5.4.297; from 5.5 before 5.10.241; from 5.11 before 5.15.190; from 5.16 before 6.1.135; from 6.2 before 6.6.88; from 6.7 before 6.12.24 — fixed in 5.10.241, 5.15.190, 5.4.297, 6.1.135, 6.12.24, 6.13.12

How to fix

Upgrade to a fixed version: Linux kernel 5.10.241, 5.15.190, 5.4.297, 6.1.135. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/2f9761a94bae33d26e6a81b31b36e7d776d93dc1
• https://git.kernel.org/stable/c/342debc12183b51773b3345ba267e9263bdfaaef
• https://git.kernel.org/stable/c/4d55144b12e742404bb3f8fee6038bafbf45619d
• https://git.kernel.org/stable/c/7a742a9506849d1c1aa71e36c89855ceddc7d58e
• https://git.kernel.org/stable/c/829c49b6b2ff45b043739168fd1245e4e1a91a30
• https://git.kernel.org/stable/c/a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31
• https://git.kernel.org/stable/c/cc71a757da78dd4aa1b4a9b19cb011833730ccf2
• https://git.kernel.org/stable/c/e73c838c80dccb9e4f19becc11d9f3cb4a27d483
• https://git.kernel.org/stable/c/eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450
• https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

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