# CVE-2026-55677: Labstack Echo authorization bypass in static file handler

Source: https://junglewise.ai/threats/cve-2026-55677-labstack-echo-authorization-bypass-in-static-file-handler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-26. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-55677 · Severity: high · CVSS 7.5 · Published 2026-06-26

Echo is a popular Go web framework used to build REST APIs and web applications. A mismatch in how the router and static file handler process URL-encoded slashes allows attackers to bypass authentication middleware protecting certain routes and download any file served by the application. By encoding slashes as %2F in the request URL, an attacker can access protected static files without proper authorization.

Technologies: [github.com/labstack/echo/v4 (Go)](https://junglewise.ai/threats/technologies/github-com-labstack-echo-v4), [github.com/labstack/echo/v5 (Go)](https://junglewise.ai/threats/technologies/github-com-labstack-echo-v5). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-55677 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55677 being exploited in the wild.

**How severe is CVE-2026-55677?** High severity, with a CVSS score of 7.5, published 26 June 2026.

**Which products and versions are affected?** github.com/labstack/echo (Go) <= 3.3.10, SEMVER:introduced=0,last_affected=3.3.10; github.com/labstack/echo/v4 (Go) < 4.15.3, SEMVER:introduced=0,fixed=4.15.3; github.com/labstack/echo/v5 (Go) < 5.2.0, SEMVER:introduced=0,fixed=5.2.0.

**Is there a fix for CVE-2026-55677?** Yes. github.com/labstack/echo/v4 (Go): upgrade to 4.15.3 or later; github.com/labstack/echo/v5 (Go): upgrade to 5.2.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55677 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55677?** Check whether you run github.com/labstack/echo (Go), github.com/labstack/echo/v4 (Go) or github.com/labstack/echo/v5 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/labstack/echo/v4 (Go): upgrade to 4.15.3 or later

  ```sh
  go get github.com/labstack/echo/v4@v4.15.3
  ```

- github.com/labstack/echo/v5 (Go): upgrade to 5.2.0 or later

  ```sh
  go get github.com/labstack/echo/v5@v5.2.0
  ```


## Technical details

Echo uses req.URL.RawPath for route matching (router.go lines 798–802), which means /admin%2Fsecret.txt is treated as a single path segment and does not match the /admin/* route pattern. Meanwhile, StaticDirectoryHandler calls url.PathUnescape() before opening files (echo.go lines 559–568), converting %2F back to / and resolving admin/secret.txt on disk. An attacker can craft requests with encoded slashes to bypass route-level authentication middleware and access protected files. No authentication or special privileges are required; the exploit works over the network against any application serving static files from a broader root directory while protecting specific route prefixes with middleware. Patches are available: versions 4.15.3+ (v4 series), 5.2.0+ (v5 series), and v3.3.10 has no patch.

## Affected products

- labstack echo v3 <= 3.3.10
- labstack echo/v4 < 4.15.3
- labstack echo/v5 < 5.2.0

## Identifiers

- CVE-2026-55677
- GHSA-vfp3-v2gw-7wfq
- GO-2026-6293

## Timeline

- 2026-08-25: disclosed: GitHub Advisory published
- 2026-06-14: patched: Patches released: echo v4.15.3 and v5.2.0; v3.x remains unpatched

## References

- [https://api.github.com/users/a-tt-om](https://api.github.com/users/a-tt-om)
- [https://github.com/a-tt-om](https://github.com/a-tt-om)
- [https://api.github.com/users/a-tt-om/gists%7B/gist_id%7D](https://api.github.com/users/a-tt-om/gists%7B/gist_id%7D)
- [https://api.github.com/users/a-tt-om/repos](https://api.github.com/users/a-tt-om/repos)
- [https://avatars.githubusercontent.com/u/92680067?v=4](https://avatars.githubusercontent.com/u/92680067?v=4)
- [https://api.github.com/users/a-tt-om/events%7B/privacy%7D](https://api.github.com/users/a-tt-om/events%7B/privacy%7D)

## Related threats

- [Echo web framework arbitrary URI scheme redirect](https://junglewise.ai/threats/cve-2026-118658-echo-is-a-go-web-framework-prior-to-4-15-2-and-5-1-1-context)
- [Echo Go web framework scheme header spoofing and HSTS bypass](https://junglewise.ai/threats/cve-2026-118657-echo-is-a-go-web-framework-prior-to-4-16-0-and-5-4-0-context)
- [Echo open redirect in sanitizeURI with trailing slash redirect](https://junglewise.ai/threats/cve-2026-118656-echo-is-a-go-web-framework-prior-to-4-16-0-and-5-4-0-sanitizeuri)
- [Echo path traversal via double URL encoding in Static middleware](https://junglewise.ai/threats/cve-2026-118655-echo-is-a-go-web-framework-prior-to-4-15-3-and-5-2-0-middleware)
- [Echo path traversal in static file handlers via dot segment normalization](https://junglewise.ai/threats/cve-2026-118654-echo-is-a-go-web-framework-prior-to-4-16-0-and-5-4-0-echo-s)