---
id: CVE-2025-68325
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop

  In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen
  and backlog of the qdisc hierarch…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop

  In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen
  and backlog of the qdisc hierarch…
severity: none
published: '2025-12-18'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T11:10:00.203'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68325'
references:
  - url: 'https://git.kernel.org/stable/c/0b6216f9b3d1c33c76f74511026e5de5385ee520'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/38abf6e931b169ea88d7529b49096f53a5dcf8fe'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3ed6c458530a547ed0c9ea0b02b19bab620be88b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/529c284cc2815c8350860e9a31722050fe7117cb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9fefc78f7f02d71810776fdeb119a05a946a27cc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a3f4e3de41a3f115db35276c6b186ccbc913934a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d01f0e072dadb02fe10f436b940dd957aff0d7d4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fcb91be52eb6e92e00b533ebd7c77fecada537e1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - exploit-available
epss: 0.00198
epssPercentile: 0.0883
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/n132/CVE-2025-68325'
  checkedAt: '2026-10-13T11:24:25.399Z'
exploitAvailable: true
ingestedAt: '2026-10-13T11:23:51.133Z'
---

## Overview

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

net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop

In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen
and backlog of the qdisc hierarchy. Its caller, cake_enqueue(), assumes
that the parent qdisc will enqueue the current packet. However, this
assumption breaks when cake_enqueue() returns NET_XMIT_CN: the parent
qdisc stops enqueuing current packet, leaving the tree qlen/backlog
accounting inconsistent. This mismatch can lead to a NULL dereference
(e.g., when the parent Qdisc is qfq_qdisc).

This patch computes the qlen/backlog delta in a more robust way by
observing the difference before and after the series of cake_drop()
calls, and then compensates the qdisc tree accounting if cake_enqueue()
returns NET_XMIT_CN.

To ensure correct compensation when ACK thinning is enabled, a new
variable is introduced to keep qlen unchanged.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.