CVE-2025-38415

Kernel crash via unchecked zero block size

Published Jul 25, 2025 · Updated Jun 18, 2026

A race in Linux Squashfs allows local users to crash the kernel while mounting a loop-device filesystem during a block-size change. During a concurrent LOOP_SET_BLOCK_SIZE ioctl and mount, squashfs_fill_super() passes a zero sb_min_blocksize() result to ffz(), setting devblksize_log2 to 64 and causing an invalid 64-bit shift in squashfs_bio_read(). The race requires local low-privileged access to manipulate the loop device and mount Squashfs; successful triggering interrupts the host kernel.

CVSS severity7.8
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race in Linux Squashfs allows local users to crash the kernel while mounting a loop-device filesystem during a block-size change. During a concurrent LOOP_SET_BLOCK_SIZE ioctl and mount, squashfs_fill_super() passes a zero sb_min_blocksize() result to ffz(), setting devblksize_log2 to 64 and causing an invalid 64-bit shift in squashfs_bio_read(). The race requires local low-privileged access to manipulate the loop device and mount Squashfs; successful triggering interrupts the host kernel.

The record

CVE
CVE-2025-38415
Published
Jul 25, 2025
Updated
Jun 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <0aff95d9bc7fb5400ca8af507429c4b067bdb425
  2. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282
  3. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <4f99357dadbf9c979ad737156ad4c37fadf7c56b
  4. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <549f9e3d7b60d53808c98b9fde49b4f46d0524a5
  5. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <5c51aa862cbeed2f3887f0382a2708956710bd68
  6. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <6abf6b78c6fb112eee495f5636ffcc350dd2ce25
  7. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <734aa85390ea693bb7eaf2240623d41b03705c84
  8. Affected versionversion=0aa666190509ffab81c202c5095a166be23961ac <db7096ea160e40d78c67fce52e7cc51bde049497
  9. Affected versionversion=2.6.29

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0aa666190509ffab81c202c5095a166be23961ac <0aff95d9bc7fb5400ca8af507429c4b067bdb425; version=0aa666190509ffab81c202c5095a166be23961ac <295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282; version=0aa666190509ffab81c202c5095a166be23961ac <4f99357dadbf9c979ad737156ad4c37fadf7c56b; version=0aa666190509ffab81c202c5095a166be23961ac <549f9e3d7b60d53808c98b9fde49b4f46d0524a5; version=0aa666190509ffab81c202c5095a166be23961ac <5c51aa862cbeed2f3887f0382a2708956710bd68; version=0aa666190509ffab81c202c5095a166be23961ac <6abf6b78c6fb112eee495f5636ffcc350dd2ce25; version=0aa666190509ffab81c202c5095a166be23961ac <734aa85390ea693bb7eaf2240623d41b03705c84; version=0aa666190509ffab81c202c5095a166be23961ac <db7096ea160e40d78c67fce52e7cc51bde049497; version=2.6.29

Published CVSS scores

7.8CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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