CVE-2025-38637 net_sched: skbprio: Remove overly strict queue assertions
A local attacker can trigger a kernel assertion failure in the skbprio qdisc, causing a system crash or denial of service.
- 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-2025-38637?
CVE-2025-38637 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 18 Apr 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: skbprio: Remove overly strict queue assertions
In the current implementation, skbprio enqueue/dequeue contains an assertion that fails under certain conditions when SKBPRIO is used as a child qdisc under TBF with specific parameters. The failure occurs because TBF sometimes peeks at packets in the child qdisc without actually dequeuing them when tokens are unavailable.
This peek operation creates a discrepancy between the parent and child qdisc queue length counters. When TBF later receives a high-priority packet, SKBPRIO's queue length may show a different value than what's reflected in its internal priority queue tracking, triggering the assertion.
The fix removes this overly strict assertions in SKBPRIO, they are not necessary at all.
Weakness: CWE-617
Which versions are affected by CVE-2025-38637?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38637?
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-2025-38637 being exploited?
There is no known exploitation of CVE-2025-38637 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-38637, DEBIAN-CVE-2025-38637, GHSA-9ghj-mrhr-8wxx, ROOT-OS-UBUNTU-2404-CVE-2025-38637, UBUNTU-CVE-2025-38637.