What is CVE-2023-4921?

CVE-2023-4921 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, classified as a Use After Free flaw (CWE-416), affecting Linux kernel versions from 3.8 onward and patched in 6.6. CVE-2023-4921 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2023-4921?

CVE-2023-4921 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2023-4921?

Yes, CVE-2023-4921 has been patched. Fixed versions include 6.6. If you are running Linux kernel 3.8 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2023-4921 actively exploited?

CVE-2023-4921 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Use After Free (CWE-416)?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/416.html

CVE-2023-4921

High

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.

Package Linux Kernel

Published 2023-09-12

Last modified 2025-02-13

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type

CWE-416

CVE-2023-4921 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 3.8 and later are affected. Fixed in 6.6 and their respective stable series.

Affected from

≥ 3.8

Fixed in

✓ 6.6 6.6.x

References

4 total

Kernel Git
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8

Exploit Mailing List Patch Vendor Advisory
Kernel
https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8

Exploit Patch Vendor Advisory
Debian Security
https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html

Mailing List Third Party Advisory
Debian Security
https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html

Mailing List Third Party Advisory

Details

CVE ID CVE-2023-4921

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2023-09-12

Modified 2025-02-13

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2023-4921?

CVE-2023-4921 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 3.8 onward and has been patched in 6.6. CVE-2023-4921 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2023-4921?

CVE-2023-4921 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2023-4921?

Yes. CVE-2023-4921 has been patched. Fixed versions include 6.6. If you are running Linux kernel 3.8 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2023-4921 actively exploited?

No. CVE-2023-4921 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.