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CISA Known Exploited Vulnerabilities

Apache HTTP Server Improper Escaping of Output Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV
2025-05-01
Remediation due
2025-05-22

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 · CISA9.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
SSVC · CISA-ADP
Exploitationactive
Automatableyes
Technical impacttotal

Affected Products

VendorProductAffected versions
Apache Software FoundationApache HTTP Server
2.4.0 to 2.4.59

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.