{"id":"CVE-2026-77281","aliases":["GHSA-j8px-rmrx-76h9"],"url":"https://o3.security/vulnerability/CVE-2026-77281","summary":"Caddy: rewrite placeholder re-expansion","details":"Caddy is an extensible server platform that uses TLS by default. In version 2.11.3 and earlier, three configuration-dependent weaknesses affect the handler and placeholder layer. In modules/caddyhttp/rewrite/rewrite.go, Rewrite.Rewrite() can pass attacker-controlled replacement bytes through buildQueryString for a second placeholder expansion when a rewrite URI ends with a literal question mark, allowing injected environment or request-variable placeholders to disclose data and, when the file provider is registered, allowing injected file placeholders to disclose readable files. The  issue is fixed in version 2.11.4.","published":"2026-09-17T21:04:58.400Z","modified":"2026-09-19T03:47:29.197043867Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/caddyserver/caddy/v2","fixedVersion":"2.11.4"}],"fix":{"url":"https://github.com/caddyserver/caddy/commit/176b043b0104cee3f894023cd5a598ac29e404bb","label":"caddyserver/caddy@176b043"},"references":[{"type":"WEB","url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77281.json"},{"type":"ADVISORY","url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-j8px-rmrx-76h9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77281"},{"type":"FIX","url":"https://github.com/caddyserver/caddy/commit/176b043b0104cee3f894023cd5a598ac29e404bb"},{"type":"FIX","url":"https://github.com/caddyserver/caddy/pull/7761"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-19T03:47:29.197043867Z"}}