Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2023-4921

CVE-2023-4921HIGH

Linux Kernel — Use-after-free in Linux kernel's net/sched: sch_qfq component

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  H  H  H    7.8   .0042   34.8     —

AFFECTED
  Product  Versions  Fixed
  Kernel   3.8 –     —

TIMELINE
  Sep 12  Reserved by Google
  Sep 12  Published (CNA: Google)
  Oct 14  EXPLOIT PUBLISHED — CVE-2023-4921 (Linux Kernel). Public exploit reference added.

CWE-416 · CNA: Google · CVSS v3.1 · 7 references · NVD status: Modified

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
September 12, 2023	Reserved	Reserved by Google
September 12, 2023	Published	Published (CNA: Google)
October 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2023-4921 (Linux Kernel). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Linux	Kernel	—	3.8	—

Weaknesses

CWE-416

References (7)

https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://cert-portal.siemens.com/productcert/html/ssa-769027.html
https://cert-portal.siemens.com/productcert/html/ssa-794697.html
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8 [Exploit, Mailing List, Patch, Vendor Advisory]
https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8 [Exploit, Patch, Vendor Advisory]
https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html [Mailing List, Third Party Advisory]
https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html [Mailing List, Third Party Advisory]

Authoritative record: CVE-2023-4921 at cve.org

Vendors: linux

Weaknesses: CWE-416

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2023-4921 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.