CVEs / CVE-2024-38475
CVE-2024-38475: Apache HTTP Server Improper Escaping of Output Vulnerability
- Known exploited in the CISA KEV catalog since 1 May 2025
- critical 9.1 CVSS 3.1 (NVD)
- EPSS 99.9% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Apache HTTP Server contains an improper escaping of output vulnerability in mod_rewrite that 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.
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 and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Apache Software Foundation Apache HTTP Server | from 2.4.0, up to and including 2.4.59 | — |
| apache http_server | from 2.4.0, up to and including 2.4.59 | — |
| netapp ontap_9 | all versions | — |
Exploitation
| In CISA KEV since | 1 May 2025 |
|---|---|
| Due date for US federal agencies | 22 May 2025 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 9.1 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NScored by NVD |
|---|---|
| Weakness | CWE-116 |
References
- CVE-2024-38475 on NVD
- CVE-2024-38475 in the CISA KEV catalog
- https://httpd.apache.org/security/vulnerabilities_24.html (cited by CISA)
- CVE-2024-38475 on OSV
- https://httpd.apache.org/security/vulnerabilities_24.html Vendor Advisory
- https://security.netapp.com/advisory/ntap-20240712-0001/ Third Party Advisory
- http://www.openwall.com/lists/oss-security/2024/07/01/8 Third Party Advisory
- https://github.com/apache/httpd/commit/9a6157d1e2f7ab15963020381054b48782bc18cf Patch
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2024-0018 Third Party Advisory
- https://www.blackhat.com/us-24/briefings/schedule/index.html#confusion-attacks-exploiting-hidden-semantic-ambiguity-in-apache-http-server-pre-recorded-40227 Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-38475 Third Party Advisory, US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.