CVE-2025-37992: debian linux Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: net_sched: Flush gso_skb list too during ->change() Previously, when reducing a qdisc's limit via the ->change() operation, only the main skb queue was trimmed, potentially leaving packets in the gso_skb list. This could result in NULL pointer dereference when we only check sch->limit against sch->q.qlen. This patch introduces a new helper, qdisc_dequeue_internal(), which ensures both the gso_skb list and the main queue are properly flushed when trimming excess packets. All relevant qdiscs (codel, fq, fq_codel, fq_pie, hhf, pie) are updated to use this helper in their ->change() routines.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	3.5 — 5.10.238
linux	linux_kernel	5.11 — 5.15.184
linux	linux_kernel	5.16 — 6.1.140
linux	linux_kernel	6.2 — 6.6.92
linux	linux_kernel	6.7 — 6.12.30
linux	linux_kernel	6.13 — 6.14.8
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/2d3cbfd6d54a2c39ce3244f33f85c595844bd7b8 https://git.kernel.org/stable/c/a7d6e0ac0a8861f6b1027488062251a8e28150fd https://git.kernel.org/stable/c/d1365ca80b012d8a7863e45949e413fb61fa4861 https://git.kernel.org/stable/c/d3336f746f196c6a53e0480923ae93939f047b6c https://git.kernel.org/stable/c/d38939ebe0d992d581acb6885c1723fa83c1fb2c https://git.kernel.org/stable/c/ea1132ccb112f51ba749c56a912f67970c2cd542 https://git.kernel.org/stable/c/fe88c7e4fc2c1cd75a278a15ffbf1689efad4e76

Other References

https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

Frequently Asked Questions

What is CVE-2025-37992? +

In the Linux kernel, the following vulnerability has been resolved: net_sched: Flush gso_skb list too during ->change() Previously, when reducing a qdisc's limit via the ->change() operation, only the main skb queue was trimmed, potentially leaving packets in the gso_skb list. This could result in NULL pointer dereference when we only check sch->limit against sch->q.qlen. This patch introduces a new helper, qdisc_dequeue_internal(), which ensures both the gso_skb list and the main queue are properly flushed when trimming excess packets. All relevant qdiscs (codel, fq, fq_codel, fq_pie, hhf, pie) are updated to use this helper in their ->change() routines. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-37992? +

CVE-2025-37992 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-37992? +

CVE-2025-37992 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-37992? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-37992