Critical Null Pointer Dereference in Linux Kernel's ksmbd Package
Summary
CVE-2025-22037: In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference in alloc_preauth_hash() The Client send malformed smb2 negotiate request. 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 and software interactions. The ksmbd module allows for SMB (Server Message Block) protocol support, enabling file sharing and network communication. This module is crucial for systems that require interoperability with Windows-based environments. However, vulnerabilities within this module can lead to severe security risks, including unauthorized access and system crashes.
Vulnerability Detail
The vulnerability identified as CVE-2025-22037 arises from a null pointer dereference in the alloc_preauth_hash() function of the ksmbd module. When a client sends a malformed SMB2 negotiate request, ksmbd responds with an error. However, if the client subsequently sends an SMB2 session setup request without the necessary preauth_info being allocated, it can lead to a system crash or unexpected behavior. This vulnerability highlights the importance of proper state management within the connection lifecycle of the ksmbd module.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid sending malformed SMB2 negotiate requests to the ksmbd service until the patch is applied. Additionally, monitoring and filtering network traffic to prevent such requests can mitigate the risk of exploitation.
Conclusion
CVE-2025-22037 is a critical vulnerability in the Linux kernel's ksmbd module that can lead to severe system issues if exploited. Users are strongly advised to update their systems to the latest patched version of the Linux kernel to ensure protection against this vulnerability. Additionally, utilizing tools like Vulert can help monitor for such vulnerabilities in real-time.
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FAQ
CVE-2025-22037 is a vulnerability in the Linux kernel's ksmbd module that can lead to a null pointer dereference, potentially causing system crashes.
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 by this vulnerability.
Exploitation of this vulnerability can lead to system crashes, unauthorized access, and disruption of services relying on the ksmbd module.
Yes, a patch is available. Users should update their Linux kernel package to the latest version to mitigate this vulnerability.
If you cannot apply the patch immediately, consider implementing network filters to block malformed SMB2 negotiate requests as a temporary workaround.
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