CVE-2025-40083
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: Fix null-deref in agg_dequeue To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c) when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return value before using it, similar to the existing approach in sch_hfsc.c. To avoid code duplication, the following changes are made: 1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static inline function. 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to include/net/pkt_sched.h so that sch_qfq can reuse it. 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing.
Affected versions
Linux kernel versions
3.8
and later are affected. Fixed in
5.4.302,
5.10.247,
5.15.197,
6.1.159,
6.6.116,
6.12.57,
6.16
and their respective stable series.
References
The following references provide additional information about CVE-2025-40083 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
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PatchKernel patch commithttps://git.kernel.org/stable/c/1bed56f089f09b465420bf23bb32985c305cfc28
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PatchKernel patch commithttps://git.kernel.org/stable/c/3c2a8994807623c7655ece205667ae2cf74940aa
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PatchKernel patch commithttps://git.kernel.org/stable/c/6ff8e74c8f8a68ec07ef837b95425dfe900d060f
Frequently asked questions
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What is CVE-2025-40083?
CVE-2025-40083 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 3.8 onward and has been patched in 5.4.302, 5.10.247, 5.15.197 and others. CVE-2025-40083 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2025-40083?
Yes — CVE-2025-40083 has been patched. Fixed versions include 5.4.302, 5.10.247, 5.15.197 and others. If you are running Linux kernel 3.8 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2025-40083 actively exploited?
No — CVE-2025-40083 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.