---
id: CVE-2026-52997
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()

  Fix dualpi2_change() to correctly enforce updated limit and memlimit
  values after a configur…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()

  Fix dualpi2_change() to correctly enforce updated limit and memlimit
  values after a configur…
severity: none
published: '2026-06-24'
updated: '2026-07-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-52997'
references:
  - url: 'https://git.kernel.org/stable/c/3042add80c2c50bd127d570b83319af612efde65'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/478ed6b7d2577439c610f91fa8759a4c878a4264'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/86cf2eba2056bcf9c41fba260e599bd95bf9943b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.0016
epssPercentile: 0.04457
ingestedAt: '2026-07-11T13:13:25.707Z'
---

## Overview

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

net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()

Fix dualpi2_change() to correctly enforce updated limit and memlimit
values after a configuration change of the dualpi2 qdisc.

Before this patch, dualpi2_change() always attempted to dequeue packets
via the root qdisc (C-queue) when reducing backlog or memory usage, and
unconditionally assumed that a valid skb will be returned. When traffic
classification results in packets being queued in the L-queue while the
C-queue is empty, this leads to a NULL skb dereference during limit or
memlimit enforcement.

This is fixed by first dequeuing from the C-queue path if it is
non-empty. Once the C-queue is empty, packets are dequeued directly from
the L-queue. Return values from qdisc_dequeue_internal() are checked for
both queues. When dequeuing from the L-queue, the parent qdisc qlen and
backlog counters are updated explicitly to keep overall qdisc statistics
consistent.

## Remediation

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