NULL Pointer Dereference Vulnerability in Apache HTTP Server (mod_heartmonitor)
Summary
DEBIAN-CVE-2026-46729: NULL Pointer Dereference vulnerability in Apache HTTP Servers mod_heartmonitor over unicast listener. Affects apache2 versions 2.4.57-2 – 2.4.69-1. No fix is published. How to fix ↓
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Background
Apache HTTP Server is a widely used open-source web server software that enables the hosting of websites and applications. It is known for its flexibility, security features, and extensive module support. The mod_heartmonitor module is designed to monitor the health of Apache servers. However, a vulnerability has been identified in this module that affects versions from 2.4.0 to 2.4.68, making it susceptible to a NULL pointer dereference issue, which could lead to server crashes.
Vulnerability Detail
The NULL Pointer Dereference vulnerability in Apache HTTP Server's mod_heartmonitor arises from improper handling of unicast listener requests. This flaw can cause the server to crash, leading to denial of service (DoS) conditions. Attackers could exploit this vulnerability by sending specially crafted requests, potentially disrupting service availability. The vulnerability affects all versions of Apache HTTP Server from 2.4.0 through 2.4.68, making it critical for users of these versions to take immediate action.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
If immediate patching is not feasible, consider disabling the mod_heartmonitor module temporarily to mitigate the risk of exploitation. This can be done by running the command: 'sudo a2dismod heartmonitor' followed by
sudo systemctl restart apache2' to restart the server without the module.
Conclusion
The NULL Pointer Dereference vulnerability in Apache HTTP Server's mod_heartmonitor poses a significant risk to server availability. Users are strongly advised to update to a patched version to mitigate this risk. Additionally, utilizing tools like Vulert can help in monitoring and managing vulnerabilities in open-source software effectively.
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FAQ
A NULL Pointer Dereference vulnerability occurs when a program attempts to access memory that has not been allocated, leading to crashes or unpredictable behavior.
You can check your Apache version by running the command 'apache2 -v' in the terminal. If your version is between 2.4.0 and 2.4.68, it is affected.
Exploitation of this vulnerability can lead to denial of service, causing the server to crash and become unavailable to users.
Yes, you can use Vulert, which monitors and alerts in real-time for open-source vulnerabilities using a manifest file like package-lock.json. You can check if your application is affected without any signup at the Vulert playground.
The CVSS score for this vulnerability is 7.5, indicating a high severity level.
References
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