CVE-2025-37915 net_sched: drr: Fix double list add in class with netem as child qdisc
A double list add in the Linux kernel DRR scheduler with netem child qdiscs causes memory corruption, potentially leading to denial of service or code execution.
- 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-2025-37915?
CVE-2025-37915 is a high-severity memory corruption vulnerability in Linux kernel, published on 20 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: drr: Fix double list add in class with netem as child qdisc
As described in Gerrard's report [1], there are use cases where a netem child qdisc will make the parent qdisc's enqueue callback reentrant. In the case of drr, there won't be a UAF, but the code will add the same classifier to the list twice, which will cause memory corruption.
In addition to checking for qlen being zero, this patch checks whether the class was already added to the active_list (cl_is_active) before adding to the list to cover for the reentrant case.
[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
Weakness: CWE-415
Which versions are affected by CVE-2025-37915?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-37915?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-37915 being exploited?
There is no known exploitation of CVE-2025-37915 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-37915, DEBIAN-CVE-2025-37915, GHSA-j8pj-vhjm-p7g6, ROOT-OS-DEBIAN-11-CVE-2025-37915, ROOT-OS-DEBIAN-12-CVE-2025-37915, ROOT-OS-UBUNTU-2204-CVE-2025-37915 and 2 more.