What is CVE-2025-21758?

CVE-2025-21758 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 2.6.26 onward and patched in 5.15.179, 6.1.129, 6.6.79 and others. CVE-2025-21758 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21758?

CVE-2025-21758 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2025-21758?

Yes, CVE-2025-21758 has been patched. Fixed versions include 5.15.179, 6.1.129, 6.6.79 and others. If you are running Linux kernel 2.6.26 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21758 actively exploited?

CVE-2025-21758 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-21758

Medium

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: add RCU protection to mld_newpack() mld_newpack() can be called without RTNL or RCU being held. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection.

Package Linux Kernel

Published 2025-02-27

Last modified 2026-05-12

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Vector string

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

Affected versions

Linux kernel versions 2.6.26 and later are affected. Fixed in 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14 and their respective stable series.

Affected from

≥ 2.6.26

Fixed in

✓ 5.15.179 5.15.x ✓ 6.1.129 6.1.x ✓ 6.6.79 6.6.x ✓ 6.12.16 6.12.x ✓ 6.13.4 6.13.x ✓ 6.14

References

The following references provide additional information about CVE-2025-21758 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Debian Security
https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
Cert-Portal
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
Kernel patch commit
https://git.kernel.org/stable/c/1b91c597b0214b1b462eb627ec02658c944623f2
Patch
Kernel patch commit
https://git.kernel.org/stable/c/25195f9d5ffcc8079ad743a50c0409dbdc48d98a
Patch
Kernel patch commit
https://git.kernel.org/stable/c/29fa42197f26a97cde29fa8c40beddf44ea5c8f3
Patch

6 patch commits total View all on NVD

Details

CVE ID CVE-2025-21758

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-02-27

Modified 2026-05-12

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21758?

CVE-2025-21758 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 2.6.26 onward and has been patched in 5.15.179, 6.1.129, 6.6.79 and others. CVE-2025-21758 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21758?

CVE-2025-21758 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2025-21758?

Yes — CVE-2025-21758 has been patched. Fixed versions include 5.15.179, 6.1.129, 6.6.79 and others. If you are running Linux kernel 2.6.26 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21758 actively exploited?

No — CVE-2025-21758 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.