Vulnerability record

CVE-2024-38475

Apache HTTP Server Improper Escaping of Output Vulnerability

CriticalExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Apache HTTP Server, fix it now.

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.

US federal civilian agencies must remediate by May 22, 2025.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Patch or advisory on github.com (opens in a new tab)

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.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Affected versions	Fixed in	Source
Apache HTTP Server	Apache Software Foundation	>= 2.4.0, < 2.4.60	2.4.60	KEV

Sources: KEV = CISA Known Exploited Vulnerabilities catalog.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2024-38475 scored CVSS 9.1: Apache HTTP Server, Apache HTTP Server Improper Escaping of Output Vulnerability
CISA lists this as exploited in the wild. Unpatched HTTP Server systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2024-38475: Apache HTTP Server, Apache HTTP Server Improper Escaping of Output Vulnerability
An official fix is now available for Apache HTTP Server. This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

httpd.apache.org https://httpd.apache.org/security/vulnerabilities_24.html
nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2024-38475
security.netapp.com https://security.netapp.com/advisory/ntap-20240712-0001/
openwall.com http://www.openwall.com/lists/oss-security/2024/07/01/8
github.com https://github.com/apache/httpd/commit/9a6157d1e2f7ab15963020381054b48782bc18cf
psirt.global.sonicwall.com https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2024-0018
blackhat.com https://www.blackhat.com/us-24/briefings/schedule/index.html#confusion-attacks-exploiting-hidden-semantic-ambi…
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-38475