What is CVE-2023-4623?

CVE-2023-4623 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 2.6.12 onward and patched in 6.6. CVE-2023-4623 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2023-4623?

CVE-2023-4623 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-2023-4623?

Yes, CVE-2023-4623 has been patched. Fixed versions include 6.6. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2023-4623 actively exploited?

CVE-2023-4623 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-2023-4623

High

A use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component can be exploited to achieve local privilege escalation. If a class with a link-sharing curve (i.e. with the HFSC_FSC flag set) has a parent without a link-sharing curve, then init_vf() will call vttree_insert() on the parent, but vttree_remove() will be skipped in update_vf(). This leaves a dangling pointer that can cause a use-after-free. We recommend upgrading past commit b3d26c5702c7d6c45456326e56d2ccf3f103e60f.

Package Linux Kernel

Published 2023-09-06

Last modified 2025-03-20

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-2023-4623 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 2.6.12 and later are affected. Fixed in 6.6 and their respective stable series.

Affected from

≥ 2.6.12

Fixed in

✓ 6.6 6.6.x

References

5 total

Kernel Git
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b3d26c5702c7d6c45456326e56d2ccf3f103e60f

Issue Tracking Mailing List Patch Vendor Advisory
Kernel
https://kernel.dance/b3d26c5702c7d6c45456326e56d2ccf3f103e60f

Patch Vendor Advisory
Packet Storm
http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html

Third Party Advisory VDB Entry
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-2023-4623

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2023-09-06

Modified 2025-03-20

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2023-4623?

CVE-2023-4623 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 2.6.12 onward and has been patched in 6.6. CVE-2023-4623 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2023-4623?

CVE-2023-4623 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-2023-4623?

Yes. CVE-2023-4623 has been patched. Fixed versions include 6.6. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2023-4623 actively exploited?

No. CVE-2023-4623 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.