Critical Connection Release Vulnerability in Linux Kernel (CVE-2025-21955)
Summary
CVE-2025-21955: In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent connection release during oplock break notification ksmbd_work could be freed when after connection release. 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 the core component of many operating systems, providing essential services for hardware and software interaction. It is known for its stability, performance, and flexibility, making it a popular choice for servers, desktops, and embedded systems. However, vulnerabilities can arise, such as CVE-2025-21955, which affects the ksmbd component responsible for SMB (Server Message Block) protocol handling.
Vulnerability Detail
CVE-2025-21955 is a vulnerability in the Linux kernel's ksmbd module that allows for a connection release during an oplock break notification. This issue can lead to the premature freeing of ksmbd_work, potentially causing instability or crashes in systems relying on this functionality. The vulnerability arises from improper management of connection states, where the reference count (r_count) of ksmbd_conn is not incremented correctly, leading to unsafe memory operations.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
Currently, there are no specific workarounds provided for this vulnerability. It is recommended to apply the patch as soon as it becomes available to mitigate any risks associated with this vulnerability.
Conclusion
CVE-2025-21955 is a critical vulnerability in the Linux kernel's ksmbd module that can lead to connection instability. Users are advised to update their systems to the patched version as soon as it becomes available to mitigate risks. Regular monitoring for vulnerabilities using tools like Vulert can help maintain system security.
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FAQ
CVE-2025-21955 is a vulnerability in the Linux kernel's ksmbd module that can lead to connection instability during oplock break notifications.
This vulnerability can cause premature memory freeing, potentially leading to system crashes or instability in applications relying on the ksmbd module.
You should update your Linux kernel package to the patched version as soon as it is available to ensure your system is secure.
Currently, there are no specific workarounds available. It is best to apply the patch once released.
You can use Vulert, which allows you to monitor and alert for open-source vulnerabilities in your software using just a manifest file. Visit Vulert Scanner to check if your application is affected without any signup.
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