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VulnerabilityPublished Updated

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

Source GCVE Database

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Not known to be exploited · CVSS 7.8 High.

Data as of 4 Nov 2026, 18:35 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 May 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.

What to do

AI-suggested

A fix has been implemented in the Linux kernel by removing the unsafe sch->q.qlen check after making qlen_notify() callbacks idempotent. Users should update their Linux kernel to the fixed version once it is available.

Description

CVE-2025-37798 is a high-severity vulnerability in the Linux kernel related to the CoDel (Controlled Delay) queuing discipline. The issue involved an unsafe check of the queue length (sch->q.qlen) before calling qdisc_tree_reduce_backlog(). This check was removed after making all qlen_notify() callbacks idempotent, which resolved the vulnerability.

References

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