Kernel Vulnerability in Linux Packages: Out-of-Bounds Memory Access Due to DACL Overflow
Summary
CVE-2025-22039: In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix overflow in dacloffset bounds check The dacloffset field was originally typed as int and used in an unchecked addition, which could overflow... Affects linux versions 6.1.106-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing essential services for hardware management, process scheduling, and system calls. It is widely used in various distributions, including Debian. The kernel's stability and security are paramount, as vulnerabilities can lead to severe system crashes or unauthorized access. This specific vulnerability affects the kernel's handling of Discretionary Access Control Lists (DACLs), which are critical for managing permissions and access rights.
Vulnerability Detail
The vulnerability identified as CVE-2025-22039 arises from an unchecked addition involving the dacloffset field, originally typed as int. This oversight can lead to an overflow, allowing attackers to bypass existing bounds checks in the functions smb_check_perm_dacl() and smb_inherit_dacl(). The consequence of this flaw is a potential out-of-bounds memory access, which could crash the kernel when the DACL pointer is dereferenced, posing a significant risk to system stability and security.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary measure, users can limit access to the affected functionalities or disable the use of DACLs until the patch is applied. However, this may not be feasible for all environments, and applying the patch is strongly recommended.
Conclusion
CVE-2025-22039 is a critical vulnerability in the Linux kernel that can lead to serious security risks. It is essential for users to update their systems to the patched version to mitigate these risks. Regular monitoring for vulnerabilities using tools like Vulert can help maintain system security.
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FAQ
CVE-2025-22039 is a vulnerability in the Linux kernel that allows for out-of-bounds memory access due to an overflow in the dacloffset bounds check.
This vulnerability can lead to kernel crashes and potential unauthorized access, compromising system stability and security.
The vulnerability affects Linux packages in Debian 11, 12, and 13.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
If immediate updates are not possible, consider limiting access to the affected functionalities or disabling DACLs as a temporary workaround.
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