CVE-2026-25766
MEDIUM
GHSA-pgvm-wxw2-hrv9
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Lifecycle Timeline
4Tags
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.
Analysis
Unauthenticated remote file read in Echo web framework versions 5.0.0-5.0.2 on Windows allows attackers to traverse outside the static root directory and access arbitrary files via backslash path sequences in requests. The vulnerability stems from improper path normalization where path.Clean() does not treat backslashes as separators, but the underlying os.Open() call on Windows does, enabling directory traversal. …
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Remediation
Within 30 days: Identify affected systems running versions 5.0.0 and apply vendor patches as part of regular patch cycle. Review file handling controls.
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