What is CVE-2025-21958?

CVE-2025-21958 is a Medium severity Linux kernel vulnerability with a CVSS score of 4.7 out of 10, affecting Linux kernel versions from 6.12 onward and patched in 6.12.20, 6.13.8 and 6.14. CVE-2025-21958 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21958?

CVE-2025-21958 has a CVSS score of 4.7 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2025-21958?

Yes, CVE-2025-21958 has been patched. Fixed versions include 6.12.20, 6.13.8 and 6.14. If you are running Linux kernel 6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21958 actively exploited?

CVE-2025-21958 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-21958

Medium

In the Linux kernel, the following vulnerability has been resolved: Revert "openvswitch: switch to per-action label counting in conntrack" Currently, ovs_ct_set_labels() is only called for confirmed conntrack entries (ct) within ovs_ct_commit(). However, if the conntrack entry does not have the labels_ext extension, attempting to allocate it in ovs_ct_get_conn_labels() for a confirmed entry triggers a warning in nf_ct_ext_add(): WARN_ON(nf_ct_is_confirmed(ct)); This happens when the conntrack entry is created externally before OVS increments net->ct.labels_used. The issue has become more likely since commit fcb1aa5163b1 ("openvswitch: switch to per-action label counting in conntrack"), which changed to use per-action label counting and increment net->ct.labels_used when a flow with ct action is added. Since there’s no straightforward way to fully resolve this issue at the moment, this reverts the commit to avoid breaking existing use cases.

Package Linux Kernel

Published 2025-04-01

Last modified 2025-10-31

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

4.7

out of 10

Medium

Attack Vector

Local

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Vector string

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

Weakness type

CWE-367

CVE-2025-21958 is classified as CWE-367

See CWE-367 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 6.12 and later are affected. Fixed in 6.12.20, 6.13.8, 6.14 and their respective stable series.

Affected from

≥ 6.12

Fixed in

✓ 6.12.20 6.12.x ✓ 6.13.8 6.13.x ✓ 6.14

References

The following references provide additional information about CVE-2025-21958 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Kernel patch commit
https://git.kernel.org/stable/c/1063ae07383c0ddc5bcce170260c143825846b03
Patch
Kernel patch commit
https://git.kernel.org/stable/c/9e79fdabd52cfce1a021640a81256878a2c516a2
Patch
Kernel patch commit
https://git.kernel.org/stable/c/d91bfc64a4886102746e74d2c6f3a61e9a77fd7d
Patch

Details

CVE ID CVE-2025-21958

Severity Medium

CVSS score 4.7 / 10

CVSS version 3.1

Published 2025-04-01

Modified 2025-10-31

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21958?

CVE-2025-21958 is a Medium severity Linux kernel vulnerability with a CVSS score of 4.7 out of 10 . It affects Linux kernel versions from 6.12 onward and has been patched in 6.12.20, 6.13.8 and 6.14. CVE-2025-21958 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21958?

CVE-2025-21958 has a CVSS score of 4.7 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2025-21958?

Yes — CVE-2025-21958 has been patched. Fixed versions include 6.12.20, 6.13.8 and 6.14. If you are running Linux kernel 6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21958 actively exploited?

No — CVE-2025-21958 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.