Apache HTTP Server mod_rewrite Improper Escaping (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 reachable via a URL. The technical impact of this mapping is potential source code disclosure or arbitrary code execution.

Exposure and applicability

This vulnerability specifically affects deployments utilizing the Apache HTTP Server where mod_rewrite is active. Because Apache HTTP Server is a widely used open-source component, exposure may extend beyond standalone installations to various third-party products that embed this server. Organizations should identify all instances of the Apache HTTP Server in their environment and determine if mod_rewrite is enabled and configured in a manner that could facilitate unauthorized filesystem mapping.

Remediation priorities

Based on our analysis, remediation should be prioritized for internet-facing servers where mod_rewrite handles complex URL routing. The following actions are recommended:

1. Apply Vendor Mitigations: Prioritize the application of patches or configuration changes as specified in the official Apache HTTP Server security documentation. This is the primary method to address the improper escaping issue.
2. Review Cloud Service Configurations: For organizations utilizing cloud-managed versions of the server, verify compliance with BOD 22-01 guidance to ensure the provider has applied necessary updates.
3. Evaluate Module Necessity: In environments where mod_rewrite is not strictly required for business operations, disabling the module would eliminate the attack surface associated with this specific CVE.

How to validate remediation

Verification must go beyond a simple version check, as a deployed patch does not inherently guarantee that the server configuration is secure. To verify that exposure has been reduced, defenders should:

• Confirm Patch Application: Verify that the installed version of the Apache HTTP Server includes the fix for CVE-2024-38475.
• Configuration Audit: Review mod_rewrite rules to ensure they do not inadvertently create paths to sensitive filesystem locations.
• Functional Testing: Use authorized testing environments to attempt to access files that should be unreachable via URL, ensuring the improper escaping flaw is no longer exploitable under current configurations.

Limits and open questions

While vendor mitigations are available, residual risk remains if the server is misconfigured or if third-party integrations introduce new mapping vulnerabilities. It remains unknown whether specific ransomware campaigns are currently leveraging this flaw. Additionally, because this affects a common open-source component, organizations must independently verify the patching status of every third-party vendor that incorporates the Apache HTTP Server into their proprietary software.

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 16, 2026 at 00:35 UTC.

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