CVE-2025-39840

High

In the Linux kernel, the following vulnerability has been resolved: audit: fix out-of-bounds read in audit_compare_dname_path() When a watch on dir=/ is combined with an fsnotify event for a single-character name directly under / (e.g., creating /a), an out-of-bounds read can occur in audit_compare_dname_path(). The helper parent_len() returns 1 for "/". In audit_compare_dname_path(), when parentlen equals the full path length (1), the code sets p = path + 1 and pathlen = 1 - 1 = 0. The subsequent loop then dereferences p[pathlen - 1] (i.e., p[-1]), causing an out-of-bounds read. Fix this by adding a pathlen > 0 check to the while loop condition to prevent the out-of-bounds access. [PM: subject tweak, sign-off email fixes]

Package Linux Kernel
Published 2025-09-19
Last modified 2026-01-14
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.1

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Weakness type

CWE-125

CVE-2025-39840 is a Out-of-bounds Read vulnerability

What is Out-of-bounds Read?

The product reads data past the end or before the beginning of the intended buffer. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.14 and later are affected. Fixed in 6.16.6, 6.17 and their respective stable series.

Affected from
≥ 6.14
Fixed in
✓ 6.16.6 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-39840 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-2025-39840?

    CVE-2025-39840 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 , classified as an Out-of-bounds Read flaw (CWE-125) . It affects Linux kernel versions from 6.14 onward and has been patched in 6.16.6 and 6.17. CVE-2025-39840 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-39840?

    CVE-2025-39840 has a CVSS score of 7.1 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:N/A:H .

  • Is there a patch available for CVE-2025-39840?

    Yes — CVE-2025-39840 has been patched. Fixed versions include 6.16.6 and 6.17. If you are running Linux kernel 6.14 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-39840 actively exploited?

    No — CVE-2025-39840 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Out-of-bounds Read (CWE-125)?

    The product reads data past the end or before the beginning of the intended buffer. View CWE-125 on MITRE CWE →

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