CVE-2025-37797 Affecting kernel-rt-64k-core package, versions <0:6.12.0-55.24.1.el10_0


Severity

Recommended
medium

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.05% (17th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-ALMALINUX10-KERNELRT64KCORE-11501761
  • published7 Aug 2025
  • disclosed28 Jul 2025

Introduced: 28 Jul 2025

NewCVE-2025-37797  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:10 kernel-rt-64k-core to version 0:6.12.0-55.24.1.el10_0 or higher.
This issue was patched in ALSA-2025:11855.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-core package and not the kernel-rt-64k-core package as distributed by AlmaLinux. See How to fix? for AlmaLinux:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

net_sched: hfsc: Fix a UAF vulnerability in class handling

This patch fixes a Use-After-Free vulnerability in the HFSC qdisc class handling. The issue occurs due to a time-of-check/time-of-use condition in hfsc_change_class() when working with certain child qdiscs like netem or codel.

The vulnerability works as follows:

  1. hfsc_change_class() checks if a class has packets (q.qlen != 0)
  2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g., codel, netem) might drop packets and empty the queue
  3. The code continues assuming the queue is still non-empty, adding the class to vttree
  4. This breaks HFSC scheduler assumptions that only non-empty classes are in vttree
  5. Later, when the class is destroyed, this can lead to a Use-After-Free

The fix adds a second queue length check after qdisc_peek_len() to verify the queue wasn't emptied.

CVSS Base Scores

version 3.1