Critical Vulnerability in Linux Kernel: 64-bit Offset Truncation Issue
Summary
CVE-2025-21665: In the Linux kernel, the following vulnerability has been resolved: filemap: avoid truncating 64-bit offset to 32 bits On 32-bit kernels, folio_seek_hole_data() was inadvertently truncating a 64-bit value to 32 bits, lea... Affects linux versions < 6.1.128-1. Fixed in 6.1.128-1. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, providing essential services for hardware management and system resources. It is widely used in various distributions, including Debian. This vulnerability affects the kernel's file handling capabilities, specifically in the folio_seek_hole_data() function, which is responsible for managing file data and offsets. The issue arises in 32-bit kernels, where a 64-bit offset is truncated, potentially leading to severe file system errors.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified where the folio_seek_hole_data() function truncates a 64-bit offset to 32 bits on 32-bit kernels. This truncation can lead to an infinite loop when writing to an XFS filesystem, causing system hangs and data loss. The vulnerability stems from improper handling of file offsets, which are critical for file operations. If exploited, this could result in significant disruptions to system stability and data integrity.
How To Fix
Minimum fixed version
6.1.128-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
Currently, there are no specific workarounds provided for this vulnerability. Users are advised to monitor their systems and apply the kernel update as soon as it becomes available.
Conclusion
The CVE-2025-21665 vulnerability in the Linux kernel poses a significant risk to systems running 32-bit kernels, particularly in Debian environments. It is crucial for users to update their kernels to the latest patched versions to avoid potential data loss and system instability. Monitoring tools like Vulert can assist in identifying vulnerabilities in real-time.
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FAQ
CVE-2025-21665 is a vulnerability in the Linux kernel that involves the truncation of a 64-bit offset to 32 bits, potentially causing infinite loops when writing to an XFS filesystem.
This vulnerability primarily affects 32-bit kernels of the Linux operating system, particularly those running on Debian versions 12 and 13.
You can use Vulert to monitor and alert for open-source vulnerabilities in your software. By using the Vulert playground, you can check if your application is affected by this vulnerability without any signup.
The risks include potential system hangs, data loss, and disruptions to file operations, which can severely impact system stability and user experience.
Yes, a patch is available. Users should update their Linux kernel to the latest version to mitigate the risks associated with this vulnerability.
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