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5.5
MEDIUM CVSS 3.1
CVE-2025-21654
ovl: support encoding fid from inode with no alias
Description

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.

INFO

Published Date :

Jan. 19, 2025, 11:15 a.m.

Last Modified :

Sept. 26, 2025, 7:48 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-21654 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM [email protected]
Solution
Update the Linux kernel to resolve a WARN_ON assertion vulnerability in overlayfs.
  • Update the Linux kernel to the latest stable version.
  • Apply the specific patch for ovl_encode_fh.
  • Test the fanotify functionality after updating.
  • Verify no new issues arise from the patch.
Public PoC/Exploit Available at Github

CVE-2025-21654 has a 1 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-21654.

URL Resource
https://git.kernel.org/stable/c/3c7c90274ae339e1ad443c9be1c67a20b80b9c76 Patch
https://git.kernel.org/stable/c/c45beebfde34aa71afbc48b2c54cdda623515037 Patch
https://git.kernel.org/stable/c/f0c0ac84de17c37e6e84da65fb920f91dada55ad Patch
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-21654 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-21654 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

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oogasawa/Utility-security

None

Java Shell

Updated: 1 month, 1 week ago
0 stars 0 fork 0 watcher
Born at : May 13, 2025, 2:51 a.m. This repo has been linked 137 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-21654 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-21654 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Sep. 26, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
    Added CWE CWE-617
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.6 up to (excluding) 6.6.74 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.10
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/3c7c90274ae339e1ad443c9be1c67a20b80b9c76 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/c45beebfde34aa71afbc48b2c54cdda623515037 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/f0c0ac84de17c37e6e84da65fb920f91dada55ad Types: Patch
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jan. 24, 2025

    Action Type Old Value New Value
    Removed Reference https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508
    Removed Reference https://git.kernel.org/stable/c/a1a541fbfa7e97c1100144db34b57553d7164ce5
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jan. 23, 2025

    Action Type Old Value New Value
    Added Reference https://git.kernel.org/stable/c/f0c0ac84de17c37e6e84da65fb920f91dada55ad
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jan. 21, 2025

    Action Type Old Value New Value
    Added Reference https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jan. 19, 2025

    Action Type Old Value New Value
    Added Description 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.
    Added Reference https://git.kernel.org/stable/c/3c7c90274ae339e1ad443c9be1c67a20b80b9c76
    Added Reference https://git.kernel.org/stable/c/a1a541fbfa7e97c1100144db34b57553d7164ce5
    Added Reference https://git.kernel.org/stable/c/c45beebfde34aa71afbc48b2c54cdda623515037
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 5.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact