Critical Code Execution Vulnerability in nginx Package
Summary
ALSA-2026:28973: Important: nginx security update. Affects nginx versions < 2:1.20.1-28.el9_8.3.alma.1. Fixed in 2:1.20.1-28.el9_8.3.alma.1. How to fix ↓
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Background
nginx is a widely-used open-source web and proxy server known for its high concurrency, performance, and low memory usage. It supports various protocols, including HTTP, and is often employed to serve static content, reverse proxy, and load balancing. The recent vulnerability poses a significant risk to users of nginx, particularly those running versions prior to the patched release.
Vulnerability Detail
The vulnerability identified as CVE-2026-9256 affects the ngx_http_rewrite_module of nginx, allowing for potential code execution and denial of service. This issue arises from improper handling of certain requests, which could enable an attacker to execute arbitrary code on the server or disrupt service availability. The ramifications of this vulnerability are severe, as it could lead to unauthorized access or complete service outages.
How To Fix
Minimum fixed version
2:1.20.1-28.el9_8.3.alma.1
This is the first release that contains the fix.
sudo dnf update nginxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, users can disable the ngx_http_rewrite_module if it is not essential for their operations. This can be done by commenting out or removing the relevant configuration lines in the nginx configuration file.
Conclusion
The nginx vulnerability CVE-2026-9256 poses a critical risk to users, allowing for code execution and denial of service. It is crucial to update to the patched version 2:1.20.1-28.el9_8.3.alma.1 to safeguard your systems. Temporary workarounds are available, but the best course of action is to apply the update as soon as possible.
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FAQ
CVE-2026-9256 is a security vulnerability in the nginx web server that allows for code execution and denial of service due to improper request handling.
You can check if your nginx installation is affected by using the Vulert playground, which allows you to monitor and alert for open-source vulnerabilities in your software without requiring installation.
Failing to address this vulnerability could lead to unauthorized access to your server, potential data breaches, and service disruptions.
Yes, you can temporarily disable the ngx_http_rewrite_module in your nginx configuration to mitigate the risk until you can apply the update.
More information can be found on the CVE page for CVE-2026-9256, which details the vulnerability's impact and the necessary updates.
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