CVE-2025-37890 Affecting kernel-default package, versions <5.3.18-150300.59.211.1


Severity

Recommended
medium

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.05% (16th percentile)

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  • Snyk IDSNYK-SLES153-KERNELDEFAULT-10750358
  • published15 Jul 2025
  • disclosed14 Jul 2025

Introduced: 14 Jul 2025

NewCVE-2025-37890  (opens in a new tab)

How to fix?

Upgrade SLES:15.3 kernel-default to version 5.3.18-150300.59.211.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-default package and not the kernel-default package as distributed by SLES. See How to fix? for SLES:15.3 relevant fixed versions and status.

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/

CVSS Base Scores

version 3.1