Critical Vulnerability in Linux Kernel: ax25_kiss_rcv() Unsharing Issue
Summary
CVE-2025-39848: In the Linux kernel, the following vulnerability has been resolved: ax25: properly unshare skbs in ax25_kiss_rcv() Bernard Pidoux reported a regression apparently caused by commit c353e8983e0d ("net: introduce per netns... 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 many operating systems, managing hardware and system resources. It provides essential services for all other parts of the system, including device drivers, file systems, and network protocols. This vulnerability affects the ax25 protocol implementation, which is used for amateur radio networking. The issue arises from improper handling of shared socket buffers (skbs), leading to potential system crashes.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the ax25 protocol's handling of socket buffers in the ax25_kiss_rcv() function. This issue was reported by Bernard Pidoux and is linked to a regression caused by a previous commit that introduced per network namespace packet chains. The vulnerability allows for the possibility of skb->dev becoming NULL, resulting in crashes during packet reception. This can lead to system instability and potential denial of service, as the kernel may crash unexpectedly when processing network packets.
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 ax25 protocol until the kernel is updated. This may involve disabling related services or configurations that rely on ax25 networking.
Conclusion
The vulnerability in the Linux kernel's ax25 protocol handling poses significant risks, including system crashes and instability. Users are strongly advised to update their kernels to the latest patched version to mitigate these risks. Temporary workarounds are available, but updating is the most effective solution.
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FAQ
The ax25 protocol is a data link layer protocol used in amateur radio networking, allowing for communication between stations.
This vulnerability can lead to system crashes when processing network packets, potentially causing denial of service.
Yes, a patch is available in version 6.16.6-1 of the Linux kernel. Users should update to this version or later.
If an immediate update is not possible, consider disabling the ax25 protocol or related services as a temporary workaround.
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