Vulnerability Description
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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Labstack | Echo | >= 5.0.0, < 5.0.3 |
| Microsoft | Windows | - |
Related Weaknesses (CWE)
References
- https://github.com/labstack/echo/commit/b1d443086ea27cf51345ec72a71e9b7e9d9ce5f1Patch
- https://github.com/labstack/echo/pull/2891Issue TrackingPatch
- https://github.com/labstack/echo/security/advisories/GHSA-pgvm-wxw2-hrv9ExploitVendor Advisory
FAQ
What is CVE-2026-25766?
CVE-2026-25766 is a vulnerability with a CVSS score of 5.3 (MEDIUM). 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 f...
How severe is CVE-2026-25766?
CVE-2026-25766 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-25766?
Check the references section above for vendor advisories and patch information. Affected products include: Labstack Echo, Microsoft Windows.