CVE-2024-38475
Apache Http Server 2.4.0 – 2.4.60
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NSummary
CVE-2024-38475 is a critical-severity Improper Encoding or Escaping of Output (CWE-116) vulnerability in Apache Http Server. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Content Injection (T1659); ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2024-38475 is an improper output escaping flaw in the mod_rewrite module of Apache HTTP Server 2.4.59 and earlier. It occurs when RewriteRule substitutions in server context use backreferences or variables as the first segment, allowing crafted URLs to resolve to filesystem paths that the server is permitted to serve but that were never intended to be directly addressable.
An unauthenticated remote attacker can send specially formed HTTP requests that exploit the mapping behavior to read arbitrary source files or execute code under the server's privileges, corresponding to the observed CVSS 9.1 rating.
Apache's security advisory and the associated patch (commit 9a6157d) recommend upgrading to a corrected release; administrators who must retain affected rules can apply the UnsafePrefixStat flag after verifying that substitutions are properly constrained. NetApp and oss-security postings reiterate the same upgrade guidance.
The EPSS score has remained near its peak value of 0.9394 since disclosure, indicating sustained exploitation interest without a pronounced post-release climb.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-37356
Vulnerability Data
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…
more
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.
- CWE(s)
- KEV Date Added
- 01 May 2025
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.1.2V1.2.1V1.2.3
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Validating that output matches expected content directly mitigates failures to properly encode or escape data for its destination context.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require proper output encoding to prevent injection and message malformation.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure coding standards explicitly require correct output encoding and escaping to preserve message structure.
Security testing can detect missing or incorrect encoding but does not itself implement the control.
Secure development life cycle mandates output encoding/escaping practices that directly prevent improper encoding.
Application security requirements include explicit rules for safe output handling and encoding.
Secure architecture principles reduce the likelihood of missing encoding but do not prescribe the actual technique.