Critical Zero Extension Vulnerability in Linux Kernel Package
Summary
DEBIAN-CVE-2026-98869: In the Linux kernel, the following vulnerability has been resolved: bpf: Infer zext_dst based on static register liveness analysis As reported in the thread [1], the verifier's 32-bit operations zero extension logic is b... Affects linux versions 6.12.100-1 – 7.3~rc7-1~exp1. No fix is published. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
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 operating system, including process management, memory management, and device control. This vulnerability affects the kernel's BPF (Berkeley Packet Filter) subsystem, which is crucial for network packet filtering and monitoring.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the BPF verifier's handling of zero extension for 32-bit operations on the s390 architecture. The issue arises from a change in the verifier's logic that tracks register liveness. This flaw can lead to a situation where an uninitialized upper half of a register may be used, allowing an attacker to inject arbitrary values. The vulnerability stems from the removal of certain liveness tracking steps, which previously ensured that the upper halves of registers were correctly zero-extended when necessary.
How To Fix
No fixed version is published for this vulnerability.
To fix this vulnerability, users should update their Linux kernel package to the latest patched version. This can typically be done using the package manager with the following command:
sudo apt-get update && sudo apt-get upgrade linux
Ensure that the system is rebooted after the update to apply the changes.
Tip — Not sure whether your app is affected? Vulert can check the versions your app actually runs. Scan free →
Workaround
As a temporary workaround, users can avoid executing BPF programs that rely on 32-bit operations until the kernel is updated. This may involve disabling certain network features or applications that utilize BPF.
Conclusion
The identified vulnerability in the Linux kernel's BPF verifier poses significant risks, allowing for potential arbitrary code execution. Users are strongly advised to update their kernel to the latest version to mitigate these risks. Temporary workarounds are available but should not replace a proper update.
See every vulnerability recorded for linux →
FAQ
The vulnerability can allow an attacker to manipulate the upper half of a register, potentially leading to arbitrary code execution or system compromise.
You can use Vulert, which monitors open-source vulnerabilities in your software. Simply upload your manifest file like package-lock.json to check for vulnerabilities.
Yes, a patch has been released. Users should update their Linux kernel package to the latest version to mitigate this vulnerability.
As a temporary measure, avoid using BPF programs that perform 32-bit operations until the kernel can be updated.
Detailed information can be found in the CVE report and the Linux kernel mailing list discussions.
References
Related vulnerabilities
Recent vulnerabilities recorded for linux.
Follow Vulert in Google
Get more Vulert vulnerability and dependency-security updates in Google Search and AI results.