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Vulnerabilities

Vulnerability · CVE-2025-38709

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

Published Sep 4, 2025 · catalog updated Oct 19, 2026 · Linux Linux

Check this week

CVE-2025-38709 is not in CISA KEV. FIRST estimates a 15.00% chance of exploitation in the next 30 days. Check whether you run Linux Linux.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
15.00%
Remediation
Version ranges on file
Affected products
cpe linux/linux kernel · vendor Linux Linux 89e4fdecb51cf5535867026274bc97de9480ade5 <139a000d20f2f38ce34296feddd641d730fe1c08

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe linux/linux kernelversion unspecified
  • vendor Linux Linux 89e4fdecb51cf5535867026274bc97de9480ade5 <139a000d20f2f38ce34296feddd641d730fe1c0889e4fdecb51cf5535867026274bc97de9480ade5 <139a000d20f2f38ce34296feddd641d730fe1c08

How to fix CVE-2025-38709

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2025-38709 is not in CISA KEV. FIRST estimates a 15.00% chance of exploitation in the next 30 days. Check whether you run Linux Linux.

Which versions are affected?

Compare what you have installed with Linux Linux 89e4fdecb51cf5535867026274bc97de9480ade5 <139a000d20f2f38ce34296feddd641d730fe1c08 89e4fdecb51cf5535867026274bc97de9480ade5 <139a000d20f2f38ce34296feddd641d730fe1c08. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 15.00%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 4, 2025 · NIST NVD

    Detected

    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 partic

  2. Oct 19, 2026 · NIST NVD

    Updated

    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 partic

Sources

  • CVE.orgVulnerability recordCVE-2025-38709

    Official CVE identifier

    cve.org
  • EUVDVulnerability recordEUVD-2025-26760

    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 bl

    euvd.enisa.europa.eu
  • NIST NVDVulnerability recordCVE-2025-38709

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 19, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.