CVE-2023-4921

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2023-09-12. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.8Exploit: NoneExposed: 0

A fix is available — apply it.

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 v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
32.2%
KEV
Not listed

Published

September 12, 2023

Last Modified

June 17, 2026

References (8)

Vendor Advisories for CVE-2023-4921(5)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(25)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-raspi-nolpae (6.5.0.1006.7) @ mantic2026-05-24ubuntu
ubuntulinux-tools-raspi2-hwe-18.04-edge (5.4.0.1096.126) @ focal2026-05-24ubuntu
ubuntulinux-tools-oem-22.04c (6.1.0.1025.26) @ jammy2026-05-24ubuntu
ubuntulinux-tools-oem-22.04d (6.5.0.1007.9) @ jammy2026-05-24ubuntu
ubuntulinux-tools-laptop-23.10 (6.5.0.1005.8) @ mantic2026-05-24ubuntu
ubuntulinux-virtual (3.13.0.197.207) @ trusty2026-05-24ubuntu
ubuntulinux-tools-nvidia-hwe-22.04-edge (6.2.0.1011.13) @ jammy2026-05-24ubuntu
ubuntulinux-virtual-lts-xenial (4.4.0.246.252) @ xenial2026-05-24ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.4.0-1032 (5.4.0-1032.36) @ focal2026-05-24ubuntu
ubuntulinux-tools-starfive (6.2.0.1007.8~22.04.1) @ jammy2026-05-24ubuntu
ubuntulinux-tools-intel-iotg-edge (5.15.0.1043.49~20.04.33) @ focal2026-05-24ubuntu
redhatkernel-0:2.6.32-754.53.1.el62024-04-16redhat
redhatkernel-0:4.18.0-477.51.1.el8_82024-03-19redhat
redhatkpatch-patch2024-03-19redhat
redhatkernel-rt-0:3.10.0-1160.114.2.rt56.1266.el72024-03-14redhat
redhatkernel-rt-0:4.18.0-193.128.1.rt13.179.el8_22024-03-12redhat
redhatkernel-0:3.10.0-1160.114.2.el72024-03-12redhat
redhatkernel-0:4.18.0-193.128.1.el8_22024-03-12redhat
redhatkernel-0:3.10.0-1062.85.1.el72024-02-27redhat
redhatkernel-0:3.10.0-957.111.1.el72024-02-26redhat
redhatkernel-rt-0:4.18.0-513.18.1.rt7.320.el8_92024-02-20redhat
redhatkernel-0:4.18.0-513.18.1.el8_92024-02-20redhat
redhatkernel-0:4.18.0-372.91.1.el8_62024-02-07redhat
redhatkernel-0:4.18.0-305.120.1.el8_42024-01-30redhat
redhatkernel-rt-0:4.18.0-305.120.1.rt7.196.el8_42024-01-30redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(20)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 12× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-07-23 02:28 UTCEG score recompute
  2. 2026-07-22 23:15 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2023-4921?
CVE-2023-4921 is a high vulnerability published on September 12, 2023. 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 qfqdequeue() due to the incorrect .peek handler of…
When was CVE-2023-4921 disclosed?
CVE-2023-4921 was first published in the National Vulnerability Database on September 12, 2023, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-4921 actively exploited?
CVE-2023-4921 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 32.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2023-4921?
CVE-2023-4921 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2023-4921?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-4921, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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