Kernel Vulnerability in Linux Package: BPF Range Refinement Issue
Summary
CVE-2025-39748: In the Linux kernel, the following vulnerability has been resolved: bpf: Forget ranges when refining tnum after JSET Syzbot reported a kernel warning due to a range invariant violation on the following BPF program. 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, responsible for managing hardware resources and providing essential services to applications. It is known for its stability, performance, and security features. However, vulnerabilities can arise, affecting its reliability. The specific issue at hand involves the BPF (Berkeley Packet Filter) subsystem, which is used for network packet filtering and monitoring. This vulnerability can lead to inconsistent register bounds during verification, potentially allowing unintended behavior in BPF programs.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the BPF subsystem where the range refinement for the JSET instruction does not handle certain cases correctly. This issue was reported by Syzbot, which highlighted a kernel warning due to a range invariant violation in a specific BPF program. The problem occurs when the verifier processes branches that should be unreachable, leading to inconsistent bounds on registers. This could potentially allow for unexpected behavior in BPF programs, posing a security risk.
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 is available.
Conclusion
The vulnerability identified in the Linux kernel's BPF subsystem poses a significant risk due to inconsistent register bounds during verification. Users are advised to update their packages to the latest patched versions to mitigate this risk. Utilizing tools like Vulert can help in monitoring and managing vulnerabilities effectively.
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FAQ
The vulnerability involves a flaw in the BPF subsystem of the Linux kernel, where range refinement for the JSET instruction can lead to inconsistent register bounds.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. By checking your manifest file like package-lock.json, you can determine if your application is affected.
If exploited, this vulnerability could lead to unexpected behavior in BPF programs, which may compromise system security or stability.
Yes, patches are available for Debian 13 (version 6.12.43-1) and Debian 14 (version 6.16.3-1). Users should update their packages to these versions.
You can use Vulert to monitor your applications for vulnerabilities in real-time without needing to access the code or installation.
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