{"id":"CVE-2026-27590","state":"PUBLISHED","title":"Caddy: Unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FastCGI transport","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.","publishedAt":"2026-02-24T16:33:41.353Z","updatedAt":"2026-02-27T20:52:00.327Z","severity":{"score":8.9,"label":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["caddyserver caddy"],"affected":[{"vendor":"caddyserver","product":"caddy","versions":[{"version":"< 2.11.1","status":"affected"}]}],"references":["https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g","https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38","https://github.com/caddyserver/caddy/releases/tag/v2.11.1"],"weaknesses":["CWE-20","CWE-180"],"ingestedAt":"2026-10-29T20:11:31.369Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/27xxx/CVE-2026-27590.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-27590","state":"PUBLISHED","datePublished":"2026-02-24T16:33:41.353Z","dateUpdated":"2026-02-27T20:52:00.327Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-02-20T17:40:28.450Z"},"containers":{"cna":{"title":"Caddy: Unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FastCGI transport","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"caddyserver","product":"caddy","versions":[{"version":"< 2.11.1","status":"affected"}]}],"references":[{"url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g","name":"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","name":"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","name":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.9,"baseSeverity":"HIGH","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","description":"CWE-20: Improper Input Validation","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-180","lang":"en","description":"CWE-180: Incorrect Behavior Order: Validate Before Canonicalize","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-02-24T16:33:41.353Z"},"source":{"advisory":"GHSA-5r3v-vc8m-m96g","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-02-27T20:51:50.628047Z","id":"CVE-2026-27590","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-02-27T20:52:00.327Z"}}]}}}