Critical Security Flaw in mod_md Package: Unintended Retry Intervals Vulnerability
Summary
RLSA-2025:23738: Important: mod_md security update. Affects mod_md versions < 1:2.4.26-4.el10_1. Fixed in 1:2.4.26-4.el10_1. How to fix ↓
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Background
The mod_md module is an integral component of the Apache HTTP Server, designed to manage common properties of domains across multiple virtual hosts. It utilizes the ACME protocol to automate the provisioning of SSL/TLS certificates, ensuring that certificates for managed domains and their respective virtual hosts are configured automatically, including during renewal processes. This functionality is crucial for maintaining secure communications over the internet.
Vulnerability Detail
The vulnerability identified as CVE-2025-55753 pertains to unintended retry intervals within the mod_md module. This flaw can lead to potential security risks, as it may allow attackers to exploit the retry mechanism, potentially leading to denial of service or other malicious activities. The vulnerability arises from improper handling of retry intervals, which could be leveraged to disrupt the normal operation of the module, affecting the security posture of the web server.
How To Fix
Minimum fixed version
1:2.4.26-4.el10_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 may consider disabling the mod_md module until the patch is applied. This can be done by running the command: 'sudo a2dismod md'. However, this should only be a short-term solution while waiting for the update.
Conclusion
The mod_md module for Apache HTTP Server has a critical vulnerability that needs immediate attention. By updating to the latest patched version, users can protect their systems from potential exploits. It is also advisable to monitor for vulnerabilities using tools like Vulert to maintain a secure environment.
See every vulnerability recorded for mod_md →
FAQ
mod_md is a module for the Apache HTTP Server that automates the management of SSL/TLS certificates using the ACME protocol.
CVE-2025-55753 refers to a security vulnerability in the mod_md module related to unintended retry intervals.
Exploitation of this vulnerability could lead to denial of service or other security issues, compromising the integrity of your web server.
Yes, a patch is available. Users should update to version 1:2.4.26-4.el10_1 to mitigate the vulnerability.
You can use Vulert, which monitors open-source vulnerabilities in your software using a manifest file like package-lock.json. Check your application for vulnerabilities at Vulert's playground.
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