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CVE-2023-25690VulnerabilityPublished Updated

CVE-2023-25690: Apache HTTP Server · HTTP Request Smuggling

Affects Apache HTTP ServerSource CVE Database V5

0

Not known to be exploited · 84% EPSS · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
84.5% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Mar 2023

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

What to do

Affected software

ProductAffectedFixed in
Apacheapache/httpdpkg:rpm/apache/httpdOther threatsAffected
  • =2.4.0
  • <=2.4.55
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Organizations should immediately upgrade Apache HTTP Server to version 2.4.56 or later, where this vulnerability is fixed. Until patching is possible, administrators should audit mod_proxy configurations, especially those using RewriteRule or ProxyPassMatch with variable substitutions involving user input, and apply strict input validation or sanitization to prevent injection of malicious request fragments. Disabling mod_proxy if not required can reduce exposure. Implementing Web Application Firewalls (WAFs) with rules to detect and block anomalous HTTP request patterns indicative of request smuggling attempts can provide additional protection. Monitoring proxy logs for irregular request patterns and unusual backend responses can help detect exploitation attempts. Network segmentation and limiting proxy access to trusted sources can further reduce risk. Finally, ensure that cache configurations are hardened to prevent poisoning, such as by validating cache keys and headers.

Description

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 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.

References

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