What is CVE-2025-21879?

CVE-2025-21879 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 6.13 onward and patched in 6.13.6 and 6.14. CVE-2025-21879 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21879?

CVE-2025-21879 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-2025-21879?

Yes, CVE-2025-21879 has been patched. Fixed versions include 6.13.6 and 6.14. If you are running Linux kernel 6.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21879 actively exploited?

CVE-2025-21879 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-2025-21879

High

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix use-after-free on inode when scanning root during em shrinking At btrfs_scan_root() we are accessing the inode's root (and fs_info) in a call to btrfs_fs_closing() after we have scheduled the inode for a delayed iput, and that can result in a use-after-free on the inode in case the cleaner kthread does the iput before we dereference the inode in the call to btrfs_fs_closing(). Fix this by using the fs_info stored already in a local variable instead of doing inode->root->fs_info.

Package Linux Kernel

Published 2025-03-27

Last modified 2025-07-06

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-2025-21879 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 6.13 and later are affected. Fixed in 6.13.6, 6.14 and their respective stable series.

Affected from

≥ 6.13

Fixed in

✓ 6.13.6 6.13.x ✓ 6.14

References

The following references provide additional information about CVE-2025-21879 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/07836bc18f4ae42da4e922244f4685561c18755e
Patch
Kernel patch commit
https://git.kernel.org/stable/c/59f37036bb7ab3d554c24abc856aabca01126414
Patch
Kernel patch commit
https://git.kernel.org/stable/c/5e79d26014f9386387575b9ed60d342057cee49b
Patch

Details

CVE ID CVE-2025-21879

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2025-03-27

Modified 2025-07-06

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21879?

CVE-2025-21879 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 6.13 onward and has been patched in 6.13.6 and 6.14. CVE-2025-21879 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21879?

CVE-2025-21879 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-2025-21879?

Yes — CVE-2025-21879 has been patched. Fixed versions include 6.13.6 and 6.14. If you are running Linux kernel 6.13 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21879 actively exploited?

No — CVE-2025-21879 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (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. View CWE-416 on MITRE CWE →