cbcvebase.
CVE-2023-25690
published 2023-03-07

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…

PriorityP189critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
ITWEXPLOITVulnCheck KEVInitial access
Exploited in the wild
EPSS
83.77%
99.7th percentile
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.

Affected

7 ranges
VendorProductVersion rangeFixed in
apachehttp_server2.4.0 – 2.4.55
apache_software_foundationapache_http_server2.4.0 – 2.4.55
debianapache2< apache2 2.4.56-1 (bookworm)apache2 2.4.56-1 (bookworm)
msrcazl3_mod_http2_2.0.29-3_on_azure_linux_3.0
msrccbl2_httpd_2.4.56-1_on_cbl_mariner_2.0
msrccm1_httpd_2.4.56-1_on_cbl_mariner_1.0
paloaltopan-os

Detection & IOCsextracted from sources · hover to see the quote

  • HTTP Request Smuggling via mod_proxy when RewriteRule or ProxyPassMatch uses a non-specific capture group that re-inserts user-supplied request-target data into the proxied URL via variable substitution
  • Canonical vulnerable config pattern to detect in Apache configs: RewriteRule with open-ended capture (.*) passed as query parameter to a proxied backend — e.g. RewriteRule "^/here/(.*)" "http://example.com:8080/elsewhere?$1" [P]
  • Attack outcomes to hunt for in proxy/access logs: access control bypass, unexpected URLs forwarded to origin servers, and cache poisoning artifacts
  • Affected Apache HTTP Server versions are 2.4.0 through 2.4.55; presence of these versions with mod_proxy enabled warrants investigation
  • ·Vulnerability is only exploitable when mod_proxy is enabled AND a RewriteRule or ProxyPassMatch with a non-specific (open-ended) capture pattern re-inserts user-controlled data into the proxied request-target via variable substitution. Not all mod_proxy deployments are affected.
  • ·Red Hat Enterprise Linux 6 httpd package is listed as Not Affected; Red Hat JBoss EAP 6 httpd22 is out of support scope — detections should be scoped accordingly.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
osv9.8CRITICAL
vulncheck9.8CRITICAL
vendor_debian9.8CRITICAL
vendor_msrc9.8CRITICAL
vendor_oracle9.8CRITICAL
vendor_redhat9.8CRITICAL
vendor_ubuntu9.8CRITICAL
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