CVE-2025-21703 Affecting linux-6.1 package, versions <6.1.129-1~deb11u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.02% (5th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-9576025
  • published1 Apr 2025
  • disclosed18 Feb 2025

Introduced: 18 Feb 2025

CVE-2025-21703  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.129-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

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

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()

qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.

CVSS Base Scores

version 3.1