A use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component can be exploited to achieve local privilege escalation.

Are you affected?

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• cpe debian/debian linux10.0
• cpe linux/linux kernelversion unspecified

How to fix CVE-2023-4921

• Recommended remediation

  No required-action text, fix commit, or clear fixed-version range is stored yet.

• Official advisories

  • CVE.org · cve.org
  • FIRST EPSS · first.org
  • NIST NVD · nvd.nist.gov

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

1. Sep 12, 2023 · NIST NVD

   Detected

   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 8fc134fee27f2

2. Oct 14, 2026 · NIST NVD

   Updated

   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 8fc134fee27f2

Sources

• CVE.orgVulnerability recordCVE-2023-4921

  Official CVE identifier

  cve.org
• FIRST EPSSExploitation probabilityCVE-2023-4921

  30-day exploitation probability 0.4%

  first.org
• NIST NVDVulnerability recordCVE-2023-4921

  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 incorrec

  nvd.nist.gov

References

• Exploit · git.kernel.org
• Exploit · kernel.dance
• Mailing List · lists.debian.org
• Mailing List · lists.debian.org

Freshness

Last verified in this catalog Oct 16, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.