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CVE-2024-38475: Apache HTTP Server Improper Escaping of Output Vulnerability

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2025-05-01
• EPSS: 100.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2024-07-01 · updated 2026-06-17
• Weakness: CWE-116

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.

Affected products

• Apache HTTP Server: from 2.4.0 before 2.4.60 — fixed in 2.4.60
• NetApp Ontap 9: all versions
• SonicWall Sma 200 Firmware: before 10.2.1.14-75sv — fixed in 10.2.1.14-75sv
• SonicWall Sma 210 Firmware: before 10.2.1.14-75sv — fixed in 10.2.1.14-75sv
• SonicWall Sma 400 Firmware: before 10.2.1.14-75sv — fixed in 10.2.1.14-75sv
• SonicWall Sma 410 Firmware: before 10.2.1.14-75sv — fixed in 10.2.1.14-75sv
• SonicWall Sma 500V Firmware: before 10.2.1.14-75sv — fixed in 10.2.1.14-75sv

How to fix

Upgrade to a fixed version: Apache HTTP Server 2.4.60; SonicWall Sma 200 Firmware 10.2.1.14-75sv; SonicWall Sma 210 Firmware 10.2.1.14-75sv; SonicWall Sma 400 Firmware 10.2.1.14-75sv; SonicWall Sma 410 Firmware 10.2.1.14-75sv; SonicWall Sma 500V Firmware 10.2.1.14-75sv. Check the vendor advisory for mitigations.

References

• https://httpd.apache.org/security/vulnerabilities_24.html
• https://security.netapp.com/advisory/ntap-20240712-0001/
• http://www.openwall.com/lists/oss-security/2024/07/01/8
• https://github.com/apache/httpd/commit/9a6157d1e2f7ab15963020381054b48782bc18cf
• https://httpd.apache.org/security/vulnerabilities_24.html
• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2024-0018
• 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://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-38475

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