CVE-2023-4921

Advisory lineage Upstream: 0 Downstream: 72
Modified
Published: 12 Sept 2023, 19:45
Last modified:25 Feb 2026, 17:20

Vulnerability Summary

Overall Risk (default)
medium
41/100
CVSS Score
7.8 HIGH
v3.1 (cve.org)
EPSS Score
0.01% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
2 found
Dark Web
Not detected

Timeline

12 Sept 2023, 19:45
Published
Vulnerability first disclosed
25 Feb 2026, 17:20
Last Modified
Vulnerability information updated

Description

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.

CVSS Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.01%• Percentile: 2%

Techniques & Countermeasures

  • CWE-416•Use After Free

    The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected Systems

  • debian•debian_linux

    10.0

  • Unknown•Kernel

    ≥ 3.8, < 6.6

  • linux•linux_kernel

    ≥ 3.8, < 4.14.326 | ≥ 4.15, < 4.19.295 | ≥ 4.20, < 5.4.257 | ≥ 5.5, < 5.10.195 | ≥ 5.11, < 5.15.132 | ≥ 5.16, < 6.1.54 | ≥ 6.2, < 6.5.4

References (4)