Echo's middleware.Static: %2F-encoded path bypasses route/group middleware guarding a statically-served path

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-118650: 0.40% estimated exploitation activity in the next 30 days; percentile 33.91 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When `middleware.Static` is mounted globally (`e.Use(middleware.Static(...))`) and an application relies on a route- or group-level middleware guard to restrict a path that also falls under the served static root, a `%2F`-encoded request bypasses that guard while the file is still served. This is the same encoding/decoding mismatch fixed for `StaticFS`/`StaticDirectoryHandler` in CVE-2026-55677 / GHSA-vfp3-v2gw-7wfq, but the fix did not cover the `middleware.Static` path. In addition, the `StaticConfig.EnablePathUnescaping` docstring states the default configuration prevents exactly this bypass, which is inaccurate for the global-mount case. This is not path traversal: no file outside the static root is accessed. The served file lives inside the static root; the issue is that access-control expectations set by a route guard are inconsistent between the literal and `%2F`-encoded forms of the same path.

Details Root cause — the router and the static handler…

Published by the source

28 Oct 2026, 19:54 UTC

Last modified by the source

28 Oct 2026, 20:15 UTC

Source last checked

29 Oct 2026, 06:45 UTC

1. Revision 2 · amended · 29 Oct 2026

   Amended from osv record GHSA-375p-5qhx-8wq4

2. Revision 1 · created · 28 Oct 2026

   Published from ghsa record GHSA-375p-5qhx-8wq4

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# Patch Next advisory brief: CVE-2026-118650

Advisory: Echo's middleware.Static: `%2F`-encoded path bypasses route/group middleware guarding a statically-served path
IDs: CVE-2026-118650, GHSA-375p-5qhx-8wq4
Record: https://patchnext.com/advisories/cve-2026-118650 (revision 2, source checked 29 Oct 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/labstack/echo/v4 4.16.0; github.com/labstack/echo/v5 5.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/labstack/echo/v4: affected < 4.16.0; fixed in 4.16.0
- Go github.com/labstack/echo/v5: affected < 5.4.0; fixed in 5.4.0

## Suggested inspection (read-only)
- Go github.com/labstack/echo/v4: check the installed version with your package manager.
- Go github.com/labstack/echo/v5: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/labstack/echo/v4, github.com/labstack/echo/v5.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-375p-5qhx-8wq4 (GitHub-reviewed advisory GHSA-375p-5qhx-8wq4 lists affected ranges: Go github.com/labstack/echo/v5 >=0 =0 <4.16.0)
- Verified: https://osv.dev/vulnerability/GHSA-375p-5qhx-8wq4 (OSV record GHSA-375p-5qhx-8wq4 lists affected ranges: Go github.com/labstack/echo/v5 >=0 =0 <4.16.0 (fixed))

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