What is CVE-2025-21648?

CVE-2025-21648 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 4.7 onward and patched in 5.10.234, 5.15.177, 6.1.125 and others. CVE-2025-21648 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21648?

CVE-2025-21648 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-2025-21648?

Yes, CVE-2025-21648 has been patched. Fixed versions include 5.10.234, 5.15.177, 6.1.125 and others. If you are running Linux kernel 4.7 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21648 actively exploited?

CVE-2025-21648 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-21648

Medium

In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: clamp maximum hashtable size to INT_MAX Use INT_MAX as maximum size for the conntrack hashtable. Otherwise, it is possible to hit WARN_ON_ONCE in __kvmalloc_node_noprof() when resizing hashtable because __GFP_NOWARN is unset. See: 0708a0afe291 ("mm: Consider __GFP_NOWARN flag for oversized kvmalloc() calls") Note: hashtable resize is only possible from init_netns.

Package Linux Kernel

Published 2025-01-19

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 4.7 and later are affected. Fixed in 5.10.234, 5.15.177, 6.1.125, 6.6.72, 6.12.10, 6.13 and their respective stable series.

Affected from

≥ 4.7

Fixed in

✓ 5.10.234 5.10.x ✓ 5.15.177 5.15.x ✓ 6.1.125 6.1.x ✓ 6.6.72 6.6.x ✓ 6.12.10 6.12.x ✓ 6.13

References

The following references provide additional information about CVE-2025-21648 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/msg00001.html
Debian Security
https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html
Cert-Portal
https://cert-portal.siemens.com/productcert/html/ssa-265688.html
Kernel patch commit
https://git.kernel.org/stable/c/5552b4fd44be3393b930434a7845d8d95a2a3c33
Patch
Kernel patch commit
https://git.kernel.org/stable/c/a965f7f0ea3ae61b9165bed619d5d6da02c75f80
Patch
Kernel patch commit
https://git.kernel.org/stable/c/b1b2353d768f1b80cd7fe045a70adee576b9b338
Patch

6 patch commits total View all on NVD

Details

CVE ID CVE-2025-21648

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-01-19

Modified 2026-05-12

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21648?

CVE-2025-21648 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 4.7 onward and has been patched in 5.10.234, 5.15.177, 6.1.125 and others. CVE-2025-21648 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21648?

CVE-2025-21648 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-2025-21648?

Yes — CVE-2025-21648 has been patched. Fixed versions include 5.10.234, 5.15.177, 6.1.125 and others. If you are running Linux kernel 4.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21648 actively exploited?

No — CVE-2025-21648 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.