Apache HTTP Server Improper Escaping of Output Vulnerability
Apache Software Foundation — Apache HTTP Server
Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure. Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected. Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.
9.1
100.0%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- Published
- Jul 1, 2024
- Modified
- Nov 3, 2025
- Added to KEV
- May 1, 2025
- Federal patch due
- May 22, 2025
CISA required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Weakness classification
Proof-of-concept & exploitation references
Weaponization
Public repositories whose name or description references CVE-2024-38475, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
No public GitHub repositories referencing CVE-2024-38475 were found at last check. Absence here is not proof no exploit exists - see the references below for vendor advisories and write-ups.
References
Frequently asked questions
What is CVE-2024-38475?
Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure. Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected. Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.
How severe is CVE-2024-38475?
CVE-2024-38475 has a CVSS base score of 9.1 out of 10 (CVSS 3.1).
Is CVE-2024-38475 actively exploited in the wild?
Yes. CVE-2024-38475 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added May 1, 2025, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2024-38475?
100.0% - meaning FIRST.org's EPSS model estimates a 100.0% probability this vulnerability will be exploited in the wild within 30 days (100% percentile among all scored CVEs).
Is there exploit tooling available for CVE-2024-38475?
Yes - a public Nuclei template referencing CVE-2024-38475 exist in public repositories we checked.
What type of vulnerability is CVE-2024-38475?
CVE-2024-38475 is classified under CWE-116 (CWE-116 Improper Encoding or Escaping of Output).
Cross-checked against
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