CVE-2024-38475
Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path.
Apache HTTP Server Improper Escaping of Output Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
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.
CISA notes
This vulnerability affects a common open-source component, third-party library, or a protocol used by different products. Please check with specific vendors for information on patching status. For more information, please see: https://httpd.apache.org/security/vulnerabilities_24.html ; https://nvd.nist.gov/vuln/detail/CVE-2024-38475
Description
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.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitation Context
as of October 17, 2026- CISA added CVE-2024-38475 to the KEV catalog 304 days after its CVE record was published. The median for entries added in 2025 is 26 days.
- It is one of 41 Apache entries in the CISA KEV catalog, and one of 3 added in 2025.
- Its current EPSS score (100.0%) is higher than that of 94% of CISA KEV entries.
Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| Apache Software Foundation | Apache Software Foundation Apache HTTP Server | 2.4.0 to 2.4.59 |
References
6 Links- https://security.netapp.com/advisory/ntap-20240712-0001/
- https://www.blackhat.com/us-24/briefings/schedule/index.html#confusion-attacks-exploiting-hidden-semantic-ambiguity-in-apache-http-server-pre-recorded-40227
- https://github.com/apache/httpd/commit/9a6157d1e2f7ab15963020381054b48782bc18cf
- http://www.openwall.com/lists/oss-security/2024/07/01/8
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2024-0018
Record Details
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Related
Tool categories
CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.