Use After Free Affecting kernel-syms package, versions <6.4.0-150600.23.53.1


Severity

Recommended
medium

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.09% (26th percentile)

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  • Snyk IDSNYK-SLES156-KERNELSYMS-10392942
  • published19 Jun 2025
  • disclosed18 Jun 2025

Introduced: 18 Jun 2025

CVE-2025-37890  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 kernel-syms to version 6.4.0-150600.23.53.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-syms package and not the kernel-syms package as distributed by SLES. See How to fix? for SLES:15.6 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