Critical SCTP Vulnerability in Linux Kernel: Null Pointer Dereference Risk
Summary
CVE-2025-21637: In the Linux kernel, the following vulnerability has been resolved: sctp: sysctl: udp_port: avoid using current->nsproxy As mentioned in a previous commit of this series, using the 'net' structure via 'current' is not re... Affects linux versions < 6.1.128-1. Fixed in 6.1.128-1. How to fix ↓
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Background
The Linux kernel is the core component of Linux operating systems, responsible for managing hardware resources and providing essential services to software applications. It supports a wide range of functionalities, including process management, memory management, and networking. The SCTP (Stream Control Transmission Protocol) is a transport layer protocol used for transmitting data over IP networks. This vulnerability affects the SCTP implementation in the Linux kernel, specifically related to the handling of network namespaces.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the SCTP implementation where the use of 'current->nsproxy' can lead to inconsistencies and potential null pointer dereferences. This occurs when the current task is exiting, causing 'current->nsproxy' to be NULL. The vulnerability can result in an 'Oops' (null pointer dereference), which may lead to system instability or crashes. The issue arises from the improper handling of the 'net' structure, which can lead to accessing incorrect network namespace information.
How To Fix
Minimum fixed version
6.1.128-1
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, no specific workaround has been provided for this vulnerability. However, users are advised to monitor their systems for updates and apply patches as they become available.
Conclusion
The CVE-2025-21637 vulnerability in the Linux kernel's SCTP implementation poses a significant risk due to potential null pointer dereferences. Users are advised to update their systems promptly to mitigate this risk and ensure stability. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
CVE-2025-21637 is a vulnerability in the Linux kernel's SCTP implementation that can lead to null pointer dereferences, potentially causing system crashes.
If exploited, this vulnerability can lead to system instability or crashes, particularly when tasks are exiting and network namespace information is accessed incorrectly.
The vulnerability affects Linux packages in Debian 12 and 13, specifically those that utilize the SCTP protocol.
Yes, users are encouraged to update their Linux packages to the latest version to receive the patch that addresses this vulnerability.
You can use Vulert, a tool that monitors open-source vulnerabilities in your software. By using the Vulert playground, you can check if your application is affected by this vulnerability without any signup.
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