CVE-2023-4921
kernel: use-after-free in sch_qfq network scheduler
Severity
ImportantRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · September 5, 2023
Updated · October 15, 2026
Description
A use-after-free flaw was found in qfq_dequeue and agg_dequeue in net/sched/sch_qfq.c in the Traffic Control (QoS) subsystem in the Linux kernel. This issue may allow a local user to crash the system or escalate their privileges on the system.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
Mitigation for this issue is to skip loading the affected module sch_qfq onto the system until we have a fix available. This can be done by a blacklist mechanism and will ensure the driver is not loaded at the boot time.
How do I blacklist a kernel module to prevent it from loading automatically?
https://access.redhat.com/solutions/41278
CVSS / CWE
CVSS 3.1 · 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 · Use After Free