Apache HTTP Server mod_rewrite Vulnerability (CVE-2024-38475)

Historical catalog analysis: CISA added this entry on May 01, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2024-38475 is an improper escaping of output vulnerability (CWE-116) located within the mod_rewrite module of the Apache HTTP Server. This flaw allows a remote actor to map URLs to filesystem locations that, while permitted to be served by the server, were not intended to be directly reachable via a URL. The reported impact of this vulnerability is the potential for source code disclosure or remote code execution.

Exposure and applicability

This vulnerability specifically affects Apache HTTP Server installations utilizing the mod_rewrite module. In healthcare environments, Apache often serves as the foundational web server for patient portals, electronic health record (EHR) administrative interfaces, and internal clinical applications.

If these servers are configured with mod_rewrite to manage URL redirection or rewriting, they may be susceptible. The risk is particularly acute for systems hosting sensitive ePHI or those acting as gateways to internal healthcare networks, as the ability to disclose source code could reveal database credentials or API keys, while remote code execution could lead to full system compromise.

Remediation priorities

Our analysis suggests that healthcare IT and security teams prioritize remediation based on the exposure of the affected server. We recommend the following prioritized actions:

1. Inventory and Patching: Identify all instances of Apache HTTP Server across the clinical and administrative environment. Prioritize applying vendor-supplied mitigations or patches to internet-facing patient portals first, followed by internal servers hosting ePHI.
2. Configuration Review: For systems where immediate patching is not feasible, review mod_rewrite configurations to identify and restrict overly permissive rewrite rules that could be leveraged to map URLs to sensitive filesystem locations.
3. Vendor Coordination: Because Apache is a common open-source component integrated into various third-party medical software packages, clinical engineering teams should contact medical device and software vendors to verify if their proprietary appliances are affected and if vendor-specific patches are required.

How to validate remediation

To verify that the risk has been reduced, administrators should employ the following methods:

• Version Verification: Confirm that the installed version of the Apache HTTP Server matches the patched version recommended by the vendor. Note that a version check alone does not guarantee security but confirms the application of the fix.
• Configuration Audit: Review the httpd.conf or relevant .htaccess files to ensure mod_rewrite is only enabled where strictly necessary and that rewrite rules follow the principle of least privilege.
• Authorized Testing: In a non-production staging environment, security teams can attempt to access known restricted filesystem paths via crafted URLs to verify that the improper escaping flaw no longer allows unauthorized mapping.

Limits and open questions

It remains unknown whether this vulnerability has been utilized in active ransomware campaigns. Furthermore, because Apache is integrated into many third-party products, the availability of patches may vary by vendor.

Applying a patch could reduce the likelihood of exploitation, but it does not eliminate all risks associated with web server configuration. Residual risk remains if other vulnerabilities exist within the application layer or if the server is misconfigured in ways unrelated to CVE-2024-38475.

Source and editorial note

CVE-2024-38475: Apache HTTP Server Improper Escaping of Output Vulnerability · Source date: May 01, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: May 04, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 13, 2026 at 00:49 UTC.

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