Understanding CVE-2024-38475: A Critical Vulnerability in Apache HTTP Server

Welcome to an important update in the field of cybersecurity, relevant particularly those managing or using Apache HTTP Servers. Today, we provide a detailed analysis of a serious vulnerability identified as CVE-2024-38475, which has been rated with a severity score of 9.1 (CRITICAL).

What is CVE-2024-38475?

CVE-2024-38475 pertains to a severe issue found in Apache HTTP Server version 2.4.59 and earlier. It involves an 'Improper escaping of output in mod_rewrite,' a key module used in Apache servers for rewriting requested URLs based on certain desired conditions. Improper escaping in this context means that the mechanism fails to prevent certain elements of data from being misunderstood or misprocessed by the server, leading to potential security breaches.

The core of the vulnerability lies in how URLs are mapped to filesystem locations that the server is configured to serve but are not meant to be accessed directly via any URL. This flaw allows attackers to potentially execute malicious code or access sensitive parts of the server filesystem, including areas where source code or configuration files reside.

This issue primarily affects substitutions in the server context when they use backreferences or variables as the first segment of the substitution, adding a layer of complexity and risk particularly for web administrators using these rewrite rules.

Impact of CVE-2024-38475

The misuse of such compromised configurations can lead to several severe repercussions including the unauthorized disclosure of source code, unauthorized execution of code, and breach of server integrity and confidentiality. Given the critical nature of this vulnerability, server administrators need to prioritize review and restructuring of potentially affected configurations.

Steps to Mitigate CVE-2024-38475

To address this vulnerability, administrators should first ensure their Apache HTTP Servers are no longer using the vulnerable versions. Upgrading to the latest patched version of the software is key. Additionally, attention should be paid to any rewrite rules, especially those involving backreferences and variables in the server context.

The Apache team has introduced a new rewrite flag, "UnsafePrefixStat", to allow admins to opt back into configurations that might appear unsafe after necessary safety checks and constraints have been applied. Appropriately constraining substitutions and carefully reviewing and testing rewrite rules before deployment are crucial steps to ensure systems are not exposed to attacks stemming from this vulnerability.


The discovery of CVE-2024-38475 underlines the continuous need for vigilance and proactive measures in server management and security. For Apache server users, staying informed about updates, understanding the configurations of your server environment, and regular audits are recommended best practices.

For in-depth assistance, patch management, and further insights about managing your Linux environments securely, visit LinuxPatch, your dedicated platform for Linux server solutions and support. Don’t let this vulnerability compromise your systems. Stay secure, stay patched.