CVE-2023-25690

CVE-2023-25690 is a critical-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 84% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-444.

Key facts

• Severity: Critical (CVSS 3.x base score 9.8)
• EPSS exploit prediction: 84% (100th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-444
• Affected product: Apache Http Server
• Published: 2023-03-07
• Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2023-25690?

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.

How severe is CVE-2023-25690?

CVE-2023-25690 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-25690 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 84% (100th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-25690?

CVE-2023-25690 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-25690?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2023-25690 published?

CVE-2023-25690 was published on 2023-03-07 and last updated on 2026-06-17.

References

• http://packetstormsecurity.com/files/176334/Apache-2.4.55-mod_proxy-HTTP-Request-Smuggling.html
• https://httpd.apache.org/security/vulnerabilities_24.html
• https://lists.debian.org/debian-lts-announce/2023/04/msg00028.html
• https://security.gentoo.org/glsa/202309-01

Affected products (1)

• cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*

More vulnerabilities in Apache Http Server

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• CVE-2005-2700 — Critical (CVSS 10.0): ssl_engine_kernel.c in mod_ssl before 2.8.24, when using "SSLVerifyClient optional" in the global virtual host…
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• CVE-1999-1293 — Critical (CVSS 10.0): mod_proxy in Apache 1.2.5 and earlier allows remote attackers to cause a denial of service via malformed FTP commands,…
• CVE-1999-0926 — Critical (CVSS 10.0): Apache allows remote attackers to conduct a denial of service via a large number of MIME headers.

All CVEs affecting Apache Http Server →

Other CWE-444 (HTTP Request/Response Smuggling) vulnerabilities

• CVE-2025-1867 — Critical (CVSS 10.0): Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in ithewei libhv allows…
• CVE-2022-22536 — Critical (CVSS 10.0): SAP NetWeaver Application Server ABAP, SAP NetWeaver Application Server Java, ABAP Platform, SAP Content Server 7.53…
• CVE-2018-3907 — Critical (CVSS 10.0): An exploitable vulnerability exists in the REST parser of video-core's HTTP server of the Samsung SmartThings Hub…
• CVE-2025-55315 — Critical (CVSS 9.9): Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized…
• CVE-2020-15049 — Critical (CVSS 9.9): An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A Request…
• CVE-2026-13763 — Critical (CVSS 9.8): Inconsistent interpretation of HTTP/2 requests in AWS Application Load Balancer with AWS WAF enabled might allow remote…

Browse all CWE-444 (HTTP Request/Response Smuggling) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

• 50.255.62.89 (ipv4-addr)
• 147.15.15.226 (ipv4-addr)
• 45.84.120.3 (ipv4-addr)
• 61.76.112.4 (ipv4-addr)
• 60.199.224.2 (ipv4-addr)
• 46.253.45.10 (ipv4-addr)
• 45.232.73.84 (ipv4-addr)
• 45.187.108.43 (ipv4-addr)