CVE-2026-25766: labstack echo Path Traversal

Vulnerability summary

CVE-2026-25766 is a medium (CVSS 5.3) Path Traversal vulnerability in labstack echo. EPSS estimates a 0.50% chance of exploitation in the next 30 days, higher than 41.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 19-02-2026
   PublishedVulnerability first disclosed.
2. 19-02-2026
   Last modifiedVulnerability information updated.

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.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.