CVE-2025-39673 Affecting kernel-modules package, versions *


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL9-KERNELMODULES-12528264
  • published6 Sept 2025
  • disclosed5 Sept 2025

Introduced: 5 Sep 2025

NewCVE-2025-39673  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-modules.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-modules package and not the kernel-modules package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

ppp: fix race conditions in ppp_fill_forward_path

ppp_fill_forward_path() has two race conditions:

  1. The ppp->channels list can change between list_empty() and list_first_entry(), as ppp_lock() is not held. If the only channel is deleted in ppp_disconnect_channel(), list_first_entry() may access an empty head or a freed entry, and trigger a panic.

  2. pch->chan can be NULL. When ppp_unregister_channel() is called, pch->chan is set to NULL before pch is removed from ppp->channels.

Fix these by using a lockless RCU approach:

  • Use list_first_or_null_rcu() to safely test and access the first list entry.
  • Convert list modifications on ppp->channels to their RCU variants and add synchronize_net() after removal.
  • Check for a NULL pch->chan before dereferencing it.

CVSS Base Scores

version 3.1