{"id":"CVE-2026-52845","revision":"6b5fe27ff9784eb9bed52e2a1b1e0c7b","records":[{"revision":"6b5fe27ff9784eb9bed52e2a1b1e0c7b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-52845","aliases":[],"title":"Caddy: FastCGI header normalization bypass in `forward_auth copy_headers`","description":"Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forward_auth copy_headers deletes the exact client-supplied identity header before copying the trusted value from the auth gateway. But when the request later goes through php_fastcgi, Caddy normalizes HTTP headers into CGI variables by replacing - with _. This lets a client send an underscore alias that survives the forward_auth delete step but becomes the same PHP/FastCGI variable. Result: a remote client can inject or sometimes override identity/group headers trusted by PHP/FastCGI applications behind Caddy. This vulnerability is fixed in 2.11.4.","state":0,"publishedAt":"2026-06-23T17:52:01.871+00:00","modifiedAt":"2026-07-15T00:46:09.498+00:00","affected":[{"ecosystem":"Vendor product","name":"caddy","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"caddyserver\",\n                    \"product\": \"caddy\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 2.11.4\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":"HIGH"}],"references":["https://github.com/caddyserver/caddy/security/advisories/GHSA-f59h-q822-g45g"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-52845","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-52845","identifiers":["CVE-2026-52845"]},"retained":false,"historicalAffected":[]}],"coverage":[]}