CyberSecBulletin
CVE-2025-38415NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2025-38415 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions db7096ea160e40d78c67fce52e7cc51bde049497, 549f9e3d7b60d53808c98b9fde49b4f46d0524a5, 5c51aa862cbeed2f3887f0382a2708956710bd68 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to db7096ea160e40d78c67fce52e7cc51bde049497 or 549f9e3d7b60d53808c98b9fde49b4f46d0524a5 or 5c51aa862cbeed2f3887f0382a2708956710bd68 or 6abf6b78c6fb112eee495f5636ffcc350dd2ce25, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.4.295 or 5.10.239 or 5.15.186 or 6.1.142, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac up to, but not including, db7096ea160e40d78c67fce52e7cc51bde049497; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 549f9e3d7b60d53808c98b9fde49b4f46d0524a5; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 5c51aa862cbeed2f3887f0382a2708956710bd68; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 6abf6b78c6fb112eee495f5636ffcc350dd2ce25; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 4f99357dadbf9c979ad737156ad4c37fadf7c56b; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 0aff95d9bc7fb5400ca8af507429c4b067bdb425; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282; 0aa666190509ffab81c202c5095a166be23961ac up to, but not including, 734aa85390ea693bb7eaf2240623d41b03705c84; and 1 more rangesdb7096ea160e40d78c67fce52e7cc51bde049497, 549f9e3d7b60d53808c98b9fde49b4f46d0524a5, 5c51aa862cbeed2f3887f0382a2708956710bd68, 6abf6b78c6fb112eee495f5636ffcc350dd2ce25, 4f99357dadbf9c979ad737156ad4c37fadf7c56b, 0aff95d9bc7fb5400ca8af507429c4b067bdb425
LinuxLinux Kernel2.6.29 up to, but not including, 5.4.295; 5.5 up to, but not including, 5.10.239; 5.11 up to, but not including, 5.15.186; 5.16 up to, but not including, 6.1.142; 6.2 up to, but not including, 6.6.94; 6.7 up to, but not including, 6.12.34; 6.13 up to, but not including, 6.15.35.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34
DebianDebian Linux11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

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().

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Out-of-bounds Write vulnerabilities

Spotted an error? Tell us.