Integer Overflow Vulnerability in Linux Kernel - cifs Package
Summary
CVE-2025-21964: In the Linux kernel, the following vulnerability has been resolved: cifs: Fix integer overflow while processing acregmax mount option User-provided mount parameter acregmax of type u32 is intended to have an upper limit,... Affects linux versions < 6.1.133-1. Fixed in 6.1.133-1. How to fix ↓
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Background
The Linux kernel is the core component of Linux operating systems, managing hardware and system resources. It provides essential services for all other parts of the operating system. The cifs (Common Internet File System) module allows for file sharing over a network, enabling users to access files on remote servers. This vulnerability affects the cifs module, specifically related to the processing of the acregmax mount option, which is intended to limit the maximum age of cached file attributes.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the cifs module where an integer overflow can occur when processing the user-provided mount parameter acregmax. This parameter, which is of type u32, is converted from seconds to jiffies before validation. If the value exceeds the upper limit, it can lead to an integer overflow, potentially allowing an attacker to manipulate system behavior or crash the kernel. This issue was discovered by the Linux Verification Center and poses a risk to system stability and security.
How To Fix
Minimum fixed version
6.1.133-1
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 apply the patch as soon as it becomes available.
Conclusion
The integer overflow vulnerability in the cifs module of the Linux kernel poses a significant risk to system stability and security. Users are encouraged to update their systems to the patched version as soon as it becomes available to protect against potential exploitation.
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FAQ
The vulnerability is an integer overflow in the cifs module of the Linux kernel, which can lead to system instability.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Exploiting this vulnerability could allow an attacker to manipulate system behavior or crash the kernel, leading to denial of service.
Yes, a patch is available for Debian 13 users in version 6.12.20-1. Users of Debian 12 should monitor for updates.
While no specific workarounds are available, it is crucial to apply the patch as soon as possible to mitigate the risk.
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