labstack echo up to 5.0.2 path traversal

Summaryinfo

A vulnerability categorized as critical has been discovered in labstack echo up to 5.0.2. The affected element is an unknown function. Executing a manipulation can lead to path traversal. This vulnerability is handled as CVE-2026-25766. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in labstack echo up to 5.0.2 and classified as critical. This vulnerability affects an unknown functionality. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. 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. As an impact it is known to affect confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-25766. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 5.0.3 eliminates this vulnerability.

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Productinfo

Vendor

• labstack

Name

• echo

Version

• 5.0.0
• 5.0.1
• 5.0.2

CPE 2.3info

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CPE 2.2info

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