http-proxy-middleware `router` host+path substring matching allows Host-header-driven backend routing bypass

Summary http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configur...

PT-2026-50734

Name of the Vulnerable Software and Affected Versions http-proxy-middleware versions 0.16.0 through 2.0.9 http-proxy-middleware versions 3.0.0 through 3.0.5 http-proxy-middleware versions 4.0.0 through 4.0.9 Description An issue exists in the router proxy-table implementation where host+path...