CVE-2023-25690
Apache Http Server 2.4.0 – 2.4.55
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-25690 is a critical-severity HTTP Request/Response Smuggling (CWE-444) vulnerability in Apache Http Server. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique LSASS Memory (T1003.001); ranked in the top 0.3% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
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-2023-25690 is an HTTP request smuggling vulnerability affecting Apache HTTP Server versions 2.4.0 through 2.4.55. It occurs in certain mod_proxy configurations that combine RewriteRule or ProxyPassMatch directives with non-specific patterns; these patterns capture portions of a user-supplied request-target and re-insert them via variable substitution into the backend request, enabling attackers to manipulate request boundaries.
An unauthenticated remote attacker can send crafted HTTP requests that exploit the smuggling condition to bypass proxy access controls, reach unintended origin URLs, or poison cache entries. The flaw carries a CVSS 3.1 score of 9.8 and is tracked under CWE-444.
Advisories from the Apache project and downstream distributions such as Debian and Gentoo recommend upgrading to version 2.4.56 or later; the official Apache security page details the affected directive patterns and confirms that the fix eliminates the variable-substitution path that permitted request splitting.
The associated EPSS score has remained elevated, with a current value of 0.6701 and a recorded peak of 0.6820; public exploit code has been posted to Packet Storm.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-29605
Vulnerability Data
Some mod_proxy configurations on Apache HTTP Server versions 2.4.0 through 2.4.55 allow a HTTP Request Smuggling attack. Configurations are affected when mod_proxy is enabled along with some form of RewriteRule or ProxyPassMatch in which a non-specific pattern matches some portion…
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of the user-supplied request-target (URL) data and is then re-inserted into the proxied request-target using variable substitution. For example, something like: RewriteEngine on RewriteRule "^/here/(.*)" "http://example.com:8080/elsewhere?$1"; [P] ProxyPassReverse /here/ http://example.com:8080/ Request splitting/smuggling could result in bypass of access controls in the proxy server, proxying unintended URLs to existing origin servers, and cache poisoning. Users are recommended to update to at least version 2.4.56 of Apache HTTP Server.
- CWE(s)
Related Threats
Threat-Actor AttributionAI
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V4.1.3V4.2.4V1.5.3V4.1.1
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.
Network monitoring can detect smuggling attempts via anomalous HTTP traffic or logs, while eliminating the inconsistency directly aids detection of such events.
Network protections can enforce consistent HTTP proxy/firewall behavior to block smuggling, and removing the weakness helps prevent unauthorized access via request smuggling.
Configuration management can enforce uniform HTTP parsing rules across intermediaries, directly mitigating inconsistent interpretation.
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.