Critical Security Update for mod_md: Addressing Unintended Retry Intervals
Summary
ALSA-2025:23739: Important: mod_md security update. Affects mod_md versions < 1:2.4.26-1.el9_7.1. Fixed in 1:2.4.26-1.el9_7.1. How to fix ↓
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Background
mod_md is a module for the Apache HTTP Server that automates the management of SSL/TLS certificates for domains hosted on the server. It utilizes the ACME protocol to streamline the process of certificate provisioning, renewal, and configuration for virtual hosts. This module is essential for maintaining secure communications over the web, ensuring that domains are properly secured with up-to-date certificates. However, a recent vulnerability has been identified that affects its functionality, specifically related to unintended retry intervals during certificate management.
Vulnerability Detail
The vulnerability, identified as CVE-2025-55753, arises from unintended retry intervals in the mod_md module. This flaw can lead to improper handling of certificate requests, potentially allowing an attacker to exploit the retry mechanism. The ramifications of this vulnerability include the risk of certificate provisioning failures, which could leave domains without valid SSL/TLS certificates, exposing them to man-in-the-middle attacks and other security threats. It is crucial for users of mod_md to understand the implications of this vulnerability and take appropriate action to mitigate risks.
How To Fix
Minimum fixed version
1:2.4.26-1.el9_7.1
This is the first release that contains the fix.
sudo dnf update mod_mdTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can manually monitor and manage certificate requests to avoid relying on the automatic retry mechanism until the patch is applied. This may involve checking the status of certificate provisioning and renewing certificates manually if necessary.
Conclusion
The mod_md module for the Apache HTTP Server has a critical vulnerability that needs immediate attention. By updating to the latest patched version, users can protect their domains from potential security threats. It is essential to stay informed about such vulnerabilities and take proactive measures to ensure the security of web applications.
See every vulnerability recorded for mod_md →
FAQ
mod_md is an Apache HTTP Server module that automates the management of SSL/TLS certificates using the ACME protocol.
CVE-2025-55753 refers to a specific vulnerability in the mod_md module that involves unintended retry intervals during certificate management.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
Failing to address this vulnerability may result in domains lacking valid SSL/TLS certificates, increasing the risk of man-in-the-middle attacks and compromising secure communications.
It is recommended to regularly check for updates and apply security patches as soon as they are available to minimize the risk of vulnerabilities.
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