{"id":"UBUNTU-CVE-2026-27590","details":"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.","modified":"2026-07-02T18:02:09.239931045Z","published":"2026-02-24T17:29:00Z","upstream":["CVE-2026-27590"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-27590"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-27590"},{"type":"REPORT","url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g"},{"type":"REPORT","url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1"},{"type":"REPORT","url":"https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38"}],"affected":[{"package":{"name":"caddy","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/caddy?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.6.2-6","2.6.2-6ubuntu0.24.04.1","2.6.2-6ubuntu0.24.04.2","2.6.2-6ubuntu0.24.04.2+esm1","2.6.2-6ubuntu0.24.04.3","2.6.2-6ubuntu0.24.04.3+esm1","2.6.2-6ubuntu0.24.04.3+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"caddy","binary_version":"2.6.2-6ubuntu0.24.04.3+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27590.json"}},{"package":{"name":"caddy","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/caddy?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.6.2-9","2.6.2-11","2.6.2-12"],"ecosystem_specific":{"binaries":[{"binary_name":"caddy","binary_version":"2.6.2-12"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27590.json"}},{"package":{"name":"caddy","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/caddy?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.6.2-12","2.6.2-14","2.6.2-14ubuntu0.26.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"caddy","binary_version":"2.6.2-14ubuntu0.26.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27590.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}