Critical Vulnerability in Linux Kernel: Shared Zerocopy State Issue
Summary
DEBIAN-CVE-2026-80977: In the Linux kernel, the following vulnerability has been resolved: net: skbuff: don't touch shared zerocopy state in skb_tx_error() skb_tx_error() completes the zerocopy uarg and clears SKBFL_ALL_ZEROCOPY, and skb_zcopy... Affects linux versions 6.1.106-1 – 7.2~rc7-1~exp1. No fix is published. How to fix ↓
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Background
The Linux kernel is a core component of the operating system, responsible for managing hardware resources and providing essential services to applications. It is widely used in various distributions, including Debian. The kernel's networking stack, particularly the skbuff (socket buffer) structure, is crucial for handling network packets efficiently. This vulnerability affects the handling of zerocopy state in shared socket buffers, which can lead to severe security implications.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the skb_tx_error() function, which improperly manages the shared zerocopy state of socket buffers (skbs). When a socket buffer is cloned, the shared state can be modified by the clone while the original skb is still in use. This can lead to a situation where a packet being forwarded has its zerocopy state incorrectly cleared, allowing unauthorized access to sensitive data. The vulnerability arises from the interaction between Open vSwitch and the kernel's networking stack, where a flow miss can strip critical markers from packets, leading to potential data exposure during local ESP delivery.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can avoid using features that rely on zerocopy socket buffers until the kernel is updated. This may involve configuring network applications to use traditional memory copying methods instead of zerocopy techniques.
Conclusion
The vulnerability CVE-2026-80977 in the Linux kernel poses significant risks due to improper handling of shared zerocopy state in socket buffers. It is crucial for users to update their systems to the patched kernel version to mitigate potential data exposure. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
CVE-2026-80977 is a vulnerability in the Linux kernel that affects the handling of shared zerocopy state in socket buffers, potentially leading to unauthorized data access.
You can use Vulert, which monitors open-source vulnerabilities in your software. By uploading your manifest file, you can check if your application is affected by this vulnerability.
The CVSS score for this vulnerability is 7.8, indicating a high level of severity.
Yes, a patched version of the Linux kernel is available. Users should update their kernel to the latest version to mitigate the vulnerability.
If an immediate update is not possible, consider implementing workarounds such as avoiding the use of zerocopy features in your network applications.
References
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