CVE-2025-38415

High

In the Linux kernel, the following vulnerability has been resolved: Squashfs: check return result of sb_min_blocksize Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug. Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails. ---- msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize); ---- sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0. As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64. This subsequently causes the UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') This commit adds a check for a 0 return by sb_min_blocksize().

Package Linux Kernel
Published 2025-07-25
Last modified 2025-12-23
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

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

Weakness type

CWE-787

CVE-2025-38415 is a Out-of-bounds Write vulnerability

What is Out-of-bounds Write?

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

Affected versions

Linux kernel versions 2.6.29 and later are affected. Fixed in 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34, 6.15.3, 6.16 and their respective stable series.

Affected from
≥ 2.6.29
Fixed in
✓ 5.4.295 5.4.x ✓ 5.10.239 5.10.x ✓ 5.15.186 5.15.x ✓ 6.1.142 6.1.x ✓ 6.6.94 6.6.x ✓ 6.12.34 6.12.x ✓ 6.15.3 6.15.x ✓ 6.16

References

The following references provide additional information about CVE-2025-38415 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2025-38415?

    CVE-2025-38415 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Out-of-bounds Write flaw (CWE-787) . It affects Linux kernel versions from 2.6.29 onward and has been patched in 5.4.295, 5.10.239, 5.15.186 and others. CVE-2025-38415 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-38415?

    CVE-2025-38415 has a CVSS score of 7.8 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:H/A:H .

  • Is there a patch available for CVE-2025-38415?

    Yes — CVE-2025-38415 has been patched. Fixed versions include 5.4.295, 5.10.239, 5.15.186 and others. If you are running Linux kernel 2.6.29 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-38415 actively exploited?

    No — CVE-2025-38415 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Out-of-bounds Write (CWE-787)?

    The product writes data past the end or before the beginning of the intended buffer. View CWE-787 on MITRE CWE →

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