{"id":"CVE-2026-27590","published":"2026-02-24T16:33:41Z","modified":"2026-02-27T20:52:00Z","title":"Caddy: Unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in…","vendor":"caddyserver","product":"caddy","tier":"tail","description":{"text":"Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's FastCGI path splitting logic computes the split index on a lowercased copy of the request path and then uses that byte index to slice the original path. This is unsafe for Unicode because `strings.ToLower()` can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect `SCRIPT_NAME`/`SCRIPT_FILENAME` and `PATH_INFO`, potentially causing a request that contains `.php` to execute a different on-disk file than intended (path confusion). In setups where an attacker can control file contents (e.g., upload features), this can lead to unintended PHP execution of non-.php files (potential RCE depending on deployment). Version 2.11.1 fixes the issue.","provenance":"source","from":"CVE.org"},"cvss":{"score":8.9,"severity":"HIGH","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.00614,"percentile":0.49281,"provenance":"source"},"cwes":[{"id":"CWE-20","name":"Improper Input Validation"},{"id":"CWE-180","name":"Incorrect Behavior Order: Validate Before Canonicalize"}],"references":[{"url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38","tags":["x_refsource_MISC"]},{"url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1","tags":["x_refsource_MISC"]}],"priority":{"score":16.1,"factors":[{"name":"EPSS percentile","points":9.86},{"name":"CVSS severity","points":6.23}]},"vendorSlug":"caddyserver","affectedVersions":[{"vendor":"caddyserver","product":"caddy","versions":["< 2.11.1"]}],"affected":[{"ecosystem":"Go","package":"github.com/caddyserver/caddy/v2","vulnerableRanges":["<2.11.1"],"patched":["2.11.1"],"from":["GHSA-5r3v-vc8m-m96g","GO-2026-4536"],"provenance":"source"}],"euvd":{"id":"EUVD-2026-8545","exploited":false,"provenance":"source"},"lineage":{"familyId":"fam-php-frankenphp-cve-2026-24895","parents":[{"from":"CVE-2026-24895","to":"CVE-2026-27590","relation":"related","confidence":"high","kind":"lineage","evidence":[{"kind":"osv-related","provenance":"source","id":"GHSA-g966-83w7-6w38","via":"related"},{"kind":"osv-related","provenance":"source","id":"GHSA-5r3v-vc8m-m96g","via":"reference","url":"https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38"},{"kind":"osv-related","provenance":"source","id":"GO-2026-4536","via":"reference","url":"https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38"}]}]}}