UBSAN Shift-Out-of-Bounds Vulnerability in Linux Kernel - Impacting Debian Packages
Summary
DEBIAN-CVE-2025-21815: In the Linux kernel, the following vulnerability has been resolved: mm/compaction: fix UBSAN shift-out-of-bounds warning syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL. Affects linux versions < 6.12.15-1. Fixed in 6.12.15-1. How to fix ↓
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Background
The Linux kernel is the core component of the Linux operating system, responsible for managing hardware resources and providing essential services to software applications. It is widely used across various distributions, including Debian 13 and 14. This vulnerability affects the memory management subsystem, specifically in the compaction process, which is crucial for efficient memory allocation and performance.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified related to a UBSAN (Undefined Behavior Sanitizer) shift-out-of-bounds warning in the function isolate_freepages_block(). This issue arises due to a bogus compound_order value that can be any value because it is unioned with flags. The absence of a MAX_PAGE_ORDER check leads to potential memory corruption and system instability, which can be exploited by attackers to cause denial of service or escalate privileges.
How To Fix
Minimum fixed version
6.12.15-1
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 mentioned for this vulnerability. The best course of action is to apply the patch by updating the kernel as described above.
Conclusion
The UBSAN shift-out-of-bounds vulnerability in the Linux kernel poses significant risks to systems running Debian 13 and 14. Users are strongly encouraged to update their kernel packages to the patched version 6.12.15-1 to mitigate potential threats. Regular monitoring using tools like Vulert can help maintain system security.
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FAQ
The vulnerability is a UBSAN shift-out-of-bounds warning in the Linux kernel's memory management, which can lead to memory corruption.
Debian 13 and 14 are affected by this vulnerability in the Linux kernel.
You can check your system's kernel version using the command 'uname -r' and compare it with the patched version 6.12.15-1.
Yes, Vulert can monitor and alert for open-source vulnerabilities in your software using just a manifest file like package-lock.json.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
References
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