CVE-2026-25766 – Echo has a Windows path traversal via backslash in middleware.Static default filesystem

CVE ID : CVE-2026-25766

Published : Feb. 19, 2026, 4:27 p.m. | 33 minutes ago

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.

Severity: 5.3 | MEDIUM

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