CVE-2025-38000
sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()
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.
INFO
Published Date :
June 6, 2025, 1:15 p.m.
Last Modified :
Dec. 16, 2025, 8:21 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update the Linux kernel to the latest version.
- Apply the specific patch for the HFSC qlen accounting.
- Verify queue accounting consistency after patching.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-38000.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-38000 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-38000
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-38000 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-38000 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Dec. 16, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-416 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5 up to (excluding) 5.10.238 *cpe:2.3:o:linux:linux_kernel:6.15:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc7:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.14.9 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.31 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.8 up to (excluding) 5.4.294 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.185 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 6.1.141 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.93 Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Added Reference Type kernel.org: https://git.kernel.org/stable/c/1034e3310752e8675e313f7271b348914008719a Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/3f981138109f63232a5fb7165938d4c945cc1b9d Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/49b21795b8e5654a7df3d910a12e1060da4c04cf Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/89c301e929a0db14ebd94b4d97764ce1d6981653 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/93c276942e75de0e5bc91576300d292e968f5a02 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/f9f593e34d2fb67644372c8f7b033bdc622ad228 Types: Patch Added Reference Type CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Types: Third Party Advisory Added Reference Type CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Types: Third Party Advisory -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Nov. 03, 2025
Action Type Old Value New Value Added Reference https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Added Reference https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 06, 2025
Action Type Old Value New Value Added 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. Added Reference https://git.kernel.org/stable/c/1034e3310752e8675e313f7271b348914008719a Added Reference https://git.kernel.org/stable/c/3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335 Added Reference https://git.kernel.org/stable/c/3f981138109f63232a5fb7165938d4c945cc1b9d Added Reference https://git.kernel.org/stable/c/49b21795b8e5654a7df3d910a12e1060da4c04cf Added Reference https://git.kernel.org/stable/c/89c301e929a0db14ebd94b4d97764ce1d6981653 Added Reference https://git.kernel.org/stable/c/93c276942e75de0e5bc91576300d292e968f5a02 Added Reference https://git.kernel.org/stable/c/f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4 Added Reference https://git.kernel.org/stable/c/f9f593e34d2fb67644372c8f7b033bdc622ad228