Critical UAF Vulnerability in Linux Kernel Affecting Debian Packages
Summary
CVE-2025-38734: In the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF on smcsk after smc_listen_out() BPF CI testing report a UAF issue: [ 16.446633] BUG: kernel NULL pointer dereference, address: 00000000... Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of the Debian operating system, responsible for managing hardware and system resources. It provides essential services for all other parts of the operating system and applications. This vulnerability specifically affects the 'linux' package across multiple Debian versions (11, 12, 13, and 14), highlighting a critical flaw that could lead to severe system instability or exploitation.
Vulnerability Detail
The vulnerability, identified as CVE-2025-38734, arises from a use-after-free (UAF) issue in the Linux kernel's networking code. This flaw occurs when the 'smc_listen_out_connected()' function releases a socket, potentially leaving a pointer to a NULL value. If an application closes the socket immediately after accepting a connection, it can lead to a NULL pointer dereference, causing a kernel panic and system crash. This vulnerability can be exploited by attackers to destabilize the system or execute arbitrary code.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid using the affected networking features until the patch is applied. Additionally, consider implementing strict access controls and monitoring to detect any unusual activity related to socket management.
Conclusion
CVE-2025-38734 represents a significant risk to systems running affected versions of the Linux kernel in Debian. Immediate action is recommended to update the kernel and mitigate potential exploitation. Users should stay informed about security updates and utilize tools like Vulert to monitor for vulnerabilities.
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FAQ
CVE-2025-38734 is a critical use-after-free vulnerability in the Linux kernel that can lead to system crashes and potential exploitation.
The vulnerability affects Debian versions 11, 12, 13, and 14.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Exploitation of this vulnerability can lead to system instability, crashes, and potential unauthorized access to system resources.
Regularly update your system and apply security patches as they become available. Monitor your system for unusual activity related to socket management.
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