{"id":"CVE-2026-25766","summary":"Echo has a Windows path traversal via backslash in middleware.Static default filesystem","details":"Echo is a Go web framework. In versions 5.0.0 through 5.0.2 on Windows, Echo’s `middleware.Static` using the default filesystem allows path traversal via backslashes, enabling unauthenticated remote file read outside the static root. In `middleware/static.go`, the requested path is unescaped and normalized with `path.Clean` (URL semantics). `path.Clean` does not treat `\\` as a path separator, so `..\\` sequences remain in the cleaned path. The resulting path is then passed to `currentFS.Open(...)`. When the filesystem is left at the default (nil), Echo uses `defaultFS` which calls `os.Open` (`echo.go:792`). On Windows, `os.Open` treats `\\` as a path separator and resolves `..\\`, allowing traversal outside the static root. Version 5.0.3 fixes the issue.","aliases":["GHSA-pgvm-wxw2-hrv9","GO-2026-4502"],"modified":"2026-05-18T05:58:37.151487504Z","published":"2026-02-19T15:49:02.402Z","related":["SUSE-SU-2026:0757-1"],"database_specific":{"cna_assigner":"GitHub_M","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25766.json","cwe_ids":["CWE-22"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25766.json"},{"type":"ADVISORY","url":"https://github.com/labstack/echo/security/advisories/GHSA-pgvm-wxw2-hrv9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25766"},{"type":"FIX","url":"https://github.com/labstack/echo/commit/b1d443086ea27cf51345ec72a71e9b7e9d9ce5f1"},{"type":"FIX","url":"https://github.com/labstack/echo/pull/2891"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/labstack/echo","events":[{"introduced":"9500f2745481e2dff1313e2e6734c488e80c13fb"},{"fixed":"b1d443086ea27cf51345ec72a71e9b7e9d9ce5f1"}]}],"versions":["v5.0.2","v5.0.1","v5.0.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-25766.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"}]}