CVE-2025-37890
What it is
In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.2% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.2% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.2% · EPSS, next 30 days
- Weakness
- CWE-416 · Use after free
- Record status
- Modified
Affected
- Linux Kernel < 5.4.294
- Linux Kernel < 5.10.238
- Linux Kernel < 5.15.182
- Linux Kernel < 6.1.138
- Linux Kernel < 6.6.90
- Linux Kernel < 6.12.28
- Linux Kernel < 6.14.6
- Linux Kernel 5.0
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-37890.md and follow it. Check whether this project is affected by CVE-2025-37890. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547
- https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421
- https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202
- https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21
- https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef
- https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5
- https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0
- https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0
References
- https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547
- https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421
- https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202
- https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21
- https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef
- https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5
- https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0
- https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0
- https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html