CVE-2025-37890

high

Published 2025-08-04 · Modified 2025-08-07

💬 Discuss on Community ✚ Propose mitigation

CVSS v3

—

CVSS v4 NEW

—

not yet in upstream

VIR risk

8.0

Description

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/

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

OS	Version	Status	Fixed in
rhel	9	fixed
rocky	8	fixed
sles		affected
rocky	9	fixed
debian	bookworm	fixed	`6.1.140-1`
debian	bullseye	fixed	`5.10.244-1`
debian	forky	fixed	`6.12.29-1`
debian	sid	fixed	`6.12.29-1`
debian	trixie	fixed	`6.12.29-1`
almalinux	8	fixed	`kernel-rt-4.18.0-553.66.1.rt7.407.el8_10.x86_64.rpm`
almalinux	9	fixed	`kernel-64k-debug-devel-matched-5.14.0-570.32.1.el9_6.aarch64.rpm`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.