CVE-2023-4921 HIGH

CVE-2023-4921: Use-after-free in Linux kernel's net/sched: sch_qfq component

Vendor Linux
Product Kernel
Weakness CWE-416
Published September 12, 2023
Last update February 25, 2026

CVSS base score

7.8/10
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

A use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component can be exploited to achieve local privilege escalation. When the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-after-free in qfq_dequeue() due to the incorrect .peek handler of sch_plug and lack of error checking in agg_dequeue(). We recommend upgrading past commit 8fc134fee27f2263988ae38920bc03da416b03d8.

Key dates

02Disclosure timeline

September 12, 2023 CVE published
February 25, 2026 Record updated