CVE-2025-37992 net_sched: Flush gso_skb list too during ->change()
A NULL pointer dereference in the Linux kernel network scheduler can cause a denial of service when reducing qdisc limits.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-37992?
CVE-2025-37992 is a medium-severity vulnerability in Debian Debian Linux, published on 26 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-476
Which versions are affected by CVE-2025-37992?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-37992?
Apply the vendor's patch.
Is CVE-2025-37992 being exploited?
There is no known exploitation of CVE-2025-37992 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-37992, DEBIAN-CVE-2025-37992, GHSA-677f-c75x-79m2, ROOT-OS-DEBIAN-11-CVE-2025-37992, ROOT-OS-DEBIAN-12-CVE-2025-37992, ROOT-OS-UBUNTU-2204-CVE-2025-37992 and 2 more.