CVE-2025-38000
In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue() When enqueuing the first packet to an HFSC class, hfsc_enqueue() calls the child qdisc's peek() operation before…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.23%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue() When enqueuing the first packet to an HFSC class, hfsc_enqueue() calls the child qdisc's peek() operation before incrementing sch->q.qlen and sch->qstats.backlog. If the child qdisc uses qdisc_peek_dequeued(), this may trigger an immediate dequeue and potential packet drop. In such cases, qdisc_tree_reduce_backlog() is called, but the HFSC qdisc's qlen and backlog have not yet been updated, leading to inconsistent queue accounting. This can leave an empty HFSC class in the active list, causing further consequences like use-after-free. This patch fixes the bug by moving the increment of sch->q.qlen and sch->qstats.backlog before the call to the child qdisc's peek() operation. This ensures that queue length and backlog are always accurate when packet drops or dequeues are triggered during the peek.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.23% probability · 13th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel · debian/debian linux
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/1034e3310752e8675e313f7271b348914008719aPatch
- https://git.kernel.org/stable/c/3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335Patch
- https://git.kernel.org/stable/c/3f981138109f63232a5fb7165938d4c945cc1b9dPatch
- https://git.kernel.org/stable/c/49b21795b8e5654a7df3d910a12e1060da4c04cfPatch
- https://git.kernel.org/stable/c/89c301e929a0db14ebd94b4d97764ce1d6981653Patch
- https://git.kernel.org/stable/c/93c276942e75de0e5bc91576300d292e968f5a02Patch
- https://git.kernel.org/stable/c/f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4Patch
- https://git.kernel.org/stable/c/f9f593e34d2fb67644372c8f7b033bdc622ad228Patch
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.