CVE-2025-37798 codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog()
A logic error in the Linux kernel's CoDel queueing discipline could lead to denial of service by incorrectly handling queue length checks during packet dequeue operations.
- 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-2025-37798?
CVE-2025-37798 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 2 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:
codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog()
After making all ->qlen_notify() callbacks idempotent, now it is safe to remove the check of qlen!=0 from both fq_codel_dequeue() and codel_qdisc_dequeue().
Which versions are affected by CVE-2025-37798?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-37798?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-37798 being exploited?
There is no known exploitation of CVE-2025-37798 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-69725, BELL-CVE-2025-37798, DEBIAN-CVE-2025-37798, GHSA-qfpx-fgcv-pjx6, ROOT-OS-DEBIAN-11-CVE-2025-37798, ROOT-OS-DEBIAN-12-CVE-2025-37798 and 2 more.