CVE-2025-21654

Medium

In the Linux kernel, the following vulnerability has been resolved: ovl: support encoding fid from inode with no alias Dmitry Safonov reported that a WARN_ON() assertion can be trigered by userspace when calling inotify_show_fdinfo() for an overlayfs watched inode, whose dentry aliases were discarded with drop_caches. The WARN_ON() assertion in inotify_show_fdinfo() was removed, because it is possible for encoding file handle to fail for other reason, but the impact of failing to encode an overlayfs file handle goes beyond this assertion. As shown in the LTP test case mentioned in the link below, failure to encode an overlayfs file handle from a non-aliased inode also leads to failure to report an fid with FAN_DELETE_SELF fanotify events. As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails if it cannot find an alias for the inode, but this failure can be fixed. ovl_encode_fh() seldom uses the alias and in the case of non-decodable file handles, as is often the case with fanotify fid info, ovl_encode_fh() never needs to use the alias to encode a file handle. Defer finding an alias until it is actually needed so ovl_encode_fh() will not fail in the common case of FAN_DELETE_SELF fanotify events.

Package Linux Kernel
Published 2025-01-19
Last modified 2025-09-26
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

Weakness type

CWE-617

CVE-2025-21654 is classified as CWE-617

See CWE-617 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 6.6 and later are affected. Fixed in 6.6.74, 6.12.10, 6.13 and their respective stable series.

Affected from
≥ 6.6
Fixed in
✓ 6.6.74 6.6.x ✓ 6.12.10 6.12.x ✓ 6.13

References

The following references provide additional information about CVE-2025-21654 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Frequently asked questions

  • What is CVE-2025-21654?

    CVE-2025-21654 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 6.6 onward and has been patched in 6.6.74, 6.12.10 and 6.13. CVE-2025-21654 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-21654?

    CVE-2025-21654 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-2025-21654?

    Yes — CVE-2025-21654 has been patched. Fixed versions include 6.6.74, 6.12.10 and 6.13. If you are running Linux kernel 6.6 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-21654 actively exploited?

    No — CVE-2025-21654 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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