Echo has CSRF Protection Bypass via MethodOverride Rewriting POST to Safe Method

Exploitation

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

CVSS

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

EPSS

• CVE-2026-118266: 0.16% estimated exploitation activity in the next 30 days; percentile 5.54 (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 The `MethodOverride` middleware accepts any non-empty string as the override target method — including safe methods (GET, HEAD, OPTIONS, TRACE) — when rewriting a POST request. When `MethodOverride` is registered before `CSRF` in the post-routing middleware chain (`e.Use()`), it rewrites the request method to a safe method before `CSRF` evaluates it. The CSRF middleware then skips token validation for the now-safe method, allowing state-changing POST handlers to execute without any CSRF check. Both the legacy token path and the modern `Sec-Fetch-Site` protection path are bypassed simultaneously.

Affected Component - `middleware/method_override.go` — `MethodOverrideConfig.ToMiddleware()` (lines 55–71): no whitelist on the override target method - `middleware/csrf.go` — `CSRFConfig.ToMiddleware()` (lines 188–189): safe-method bypass branch reads the already-rewritten method - `middleware/csrf.go` — `checkSecFetchSiteRequest()` (line 283): `Sec-Fetch-Site` safe check also…

Published by the source

28 Oct 2026, 19:53 UTC

Last modified by the source

28 Oct 2026, 20:00 UTC

Source last checked

29 Oct 2026, 06:45 UTC

1. Revision 2 · amended · 29 Oct 2026

   Amended from osv record GHSA-r7w9-592q-9vg4

2. Revision 1 · created · 28 Oct 2026

   Published from ghsa record GHSA-r7w9-592q-9vg4

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# Patch Next advisory brief: CVE-2026-118266

Advisory: Echo has CSRF Protection Bypass via MethodOverride Rewriting POST to Safe Method
IDs: CVE-2026-118266, GHSA-r7w9-592q-9vg4
Record: https://patchnext.com/advisories/cve-2026-118266 (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: Medium (CVSS 5.3)
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 >= 5.0.0, < 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-r7w9-592q-9vg4 (GitHub-reviewed advisory GHSA-r7w9-592q-9vg4 lists affected ranges: Go github.com/labstack/echo/v5 >=5.0.0 =0 <4.16.0)
- Verified: https://osv.dev/vulnerability/GHSA-r7w9-592q-9vg4 (OSV record GHSA-r7w9-592q-9vg4 lists affected ranges: Go github.com/labstack/echo/v5 >=5.0.0 =0 <4.16.0 (fixed))

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