Critical Vulnerability in Linux Kernel: Squashfs Block Size Handling
Summary
CVE-2025-38415: 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. Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
The Linux kernel is the core component of the Linux operating system, responsible for managing hardware and system resources. It provides essential services for all other parts of the operating system, including process management, memory management, and device control. The Squashfs filesystem is a compressed read-only file system for Linux, allowing efficient storage and access to files. However, a vulnerability has been identified in the Squashfs implementation that can lead to undefined behavior under specific conditions.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the Squashfs filesystem related to the handling of block sizes. The issue arises when multiple processes attempt to mount a Squashfs filesystem simultaneously while issuing an ioctl to set the block size. This race condition can lead to a situation where the block size is incorrectly set to zero, causing subsequent operations to fail. Specifically, the function sb_min_blocksize can return zero, leading to a shift-out-of-bounds error in the code. This can potentially allow an attacker to exploit the vulnerability, resulting in system instability or crashes.
How To Fix
No fixed version is published for this vulnerability.
Tip — Not sure whether your app is affected? Vulert can check the versions your app actually runs. Scan free →
Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. It is advisable to avoid simultaneous mounting of Squashfs filesystems until the patch is applied.
Conclusion
The vulnerability in the Linux kernel's Squashfs filesystem presents a significant risk due to its potential to cause system instability. It is crucial for users to update their systems to the patched version to mitigate this risk. Regular monitoring using tools like Vulert can help in identifying and addressing such vulnerabilities promptly.
See every vulnerability recorded for linux →
FAQ
The vulnerability is a race condition in the Squashfs filesystem that can lead to a shift-out-of-bounds error due to improper handling of block sizes.
The vulnerability affects the Linux kernel in Debian 11, 12, and 13, with a specific fix available for Debian 13.
You can use Vulert to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected by this vulnerability.
Exploitation of this vulnerability can lead to system instability, crashes, or potentially allow an attacker to execute arbitrary code.
While there are no specific workarounds, it is advisable to avoid simultaneous operations that involve mounting Squashfs filesystems.
Related vulnerabilities
Recent vulnerabilities recorded for linux.
