Race Condition Vulnerability in ksmbd of Linux Kernel - CVE-2025-40039
Summary
DEBIAN-CVE-2025-40039: In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix race condition in RPC handle list access The 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd session. 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 control, and system security. It includes various subsystems, one of which is ksmbd, a server that implements the SMB protocol for file sharing. This vulnerability affects the ksmbd subsystem, specifically in the management of RPC handles, which are critical for session management and data integrity.
Vulnerability Detail
In the Linux kernel's ksmbd subsystem, a race condition vulnerability exists due to improper locking mechanisms when accessing the 'sess->rpc_handle_list' XArray. The issue arises from the use of a read lock during modifications, which can lead to data corruption and inconsistent reads. Specifically, the functions ksmbd_session_rpc_open() and ksmbd_session_rpc_method() fail to adequately protect against concurrent access, potentially resulting in use-after-free errors and data integrity issues.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. The best course of action is to apply the patch as soon as it is available.
Conclusion
The CVE-2025-40039 vulnerability in the ksmbd subsystem of the Linux kernel poses significant risks due to improper locking mechanisms leading to race conditions. It is essential to update the affected Linux packages to ensure system integrity and security.
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FAQ
CVE-2025-40039 is a vulnerability in the ksmbd subsystem of the Linux kernel that allows for potential race conditions due to improper locking mechanisms.
This vulnerability can lead to data corruption, inconsistent reads, and potential use-after-free errors, which may compromise system stability and security.
The vulnerability affects Linux versions in Debian 12, 13, and 14.
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 without needing to sign up.
While there are no specific workarounds, it is crucial to prioritize applying the patch once available to mitigate the risks associated with this vulnerability.
References
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