{"cve":"CVE-2026-27590","nvd":{"published":"2026-02-24T17:29:04.493","modified":"2026-06-17T10:27:21.350","status":"Analyzed","description":"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.","cvss_v4":{"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","score":8.9},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-20","CWE-180"],"references":["https://github.com/caddyserver/caddy/releases/tag/v2.11.1","https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g","https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38"],"products":["caddyserver:caddy"],"source":"nvd","synced_at":"2026-10-19T22:24:17.937441719+00:00"},"epss":{"cve":"CVE-2026-27590","score":0.00614,"percentile":0.49445,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-5r3v-vc8m-m96g","url":"https://osv.dev/vulnerability/GHSA-5r3v-vc8m-m96g","summary":"Caddy: Unicode case-folding length expansion causes incorrect split_path index in FastCGI transport","modified":"2026-02-27T19:55:10Z","packages":[{"ecosystem":"Go","name":"github.com/caddyserver/caddy/v2","purl":"pkg:golang/github.com/caddyserver/caddy/v2","ranges":["<2.11.1"],"fixed":["2.11.1"]}]},{"id":"GO-2026-4536","url":"https://osv.dev/vulnerability/GO-2026-4536","summary":"Unicode case-folding causes incorrect split_path index in github.com/caddyserver/caddy/v2","modified":"2026-02-26T19:11:19.880583Z","packages":[{"ecosystem":"Go","name":"github.com/caddyserver/caddy/v2","purl":"pkg:golang/github.com/caddyserver/caddy/v2","ranges":["<2.11.1"],"fixed":["2.11.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}