CVE-2025-38709

Medium

In the Linux kernel, the following vulnerability has been resolved: loop: Avoid updating block size under exclusive owner Syzbot came up with a reproducer where a loop device block size is changed underneath a mounted filesystem. This causes a mismatch between the block device block size and the block size stored in the superblock causing confusion in various places such as fs/buffer.c. The particular issue triggered by syzbot was a warning in __getblk_slow() due to requested buffer size not matching block device block size. Fix the problem by getting exclusive hold of the loop device to change its block size. This fails if somebody (such as filesystem) has already an exclusive ownership of the block device and thus prevents modifying the loop device under some exclusive owner which doesn't expect it.

Package Linux Kernel
Published 2025-09-04
Last modified 2025-12-03
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 4.14 and later are affected. Fixed in 6.6.109, 6.12.43, 6.15.11, 6.16.2, 6.17 and their respective stable series.

Affected from
≥ 4.14
Fixed in
✓ 6.6.109 6.6.x ✓ 6.12.43 6.12.x ✓ 6.15.11 6.15.x ✓ 6.16.2 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-38709 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

5 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2025-38709?

    CVE-2025-38709 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 4.14 onward and has been patched in 6.6.109, 6.12.43, 6.15.11 and others. CVE-2025-38709 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-38709?

    CVE-2025-38709 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-2025-38709?

    Yes — CVE-2025-38709 has been patched. Fixed versions include 6.6.109, 6.12.43, 6.15.11 and others. If you are running Linux kernel 4.14 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-38709 actively exploited?

    No — CVE-2025-38709 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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