Ech0's Unauthenticated Like Endpoint Enables Arbitrary Engagement Metric Inflation

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary No authentication is required to invoke PUT /api/echo/like/:id. The handler is registered on the public router group. The service increments favcount for the given echo without checking identity, without a per-user limit, and without CSRF tokens. A remote client can arbitrarily inflate like metrics with repeated requests. Description Root cause: The like endpoint is explicitly public (PublicRouterGroup). LikeEcho in the service layer only runs a repository increment inside a transaction—no viewer/user binding. Security boundary that fails: Integrity of engagement metrics (likes) and any trust that “likes” represent distinct or authenticated users. Exploitation: Discover or guess a public echo UUID (timeline, API, share link) → send unauthenticated PUT repeatedly → favcount increases linearly. Affected files | Public route registration | internal/router/echo.go | | Like mutation (no auth check) | internal/service/echo/echo.go | | Handler | internal/handler/echo/echo.go |…

Published by the source

7 May 2026, 21:21 UTC

Last modified by the source

7 May 2026, 21:21 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rgj7-vg8v-j4wr

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# Patch Next advisory brief: GHSA-rgj7-vg8v-j4wr

Advisory: Ech0's Unauthenticated Like Endpoint Enables Arbitrary Engagement Metric Inflation
IDs: GHSA-rgj7-vg8v-j4wr
Record: https://patchnext.com/advisories/ghsa-rgj7-vg8v-j4wr (revision 1, source checked 26 Oct 2026, 15:20 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/lin-snow/ech0 1.4.8-0.20260503040728-a7e8b8e84bd1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/lin-snow/ech0: affected < 1.4.8-0.20260503040728-a7e8b8e84bd1; fixed in 1.4.8-0.20260503040728-a7e8b8e84bd1

## Suggested inspection (read-only)
- Go github.com/lin-snow/ech0: 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/lin-snow/ech0.
- 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-rgj7-vg8v-j4wr (GitHub-reviewed advisory GHSA-rgj7-vg8v-j4wr lists affected ranges: Go github.com/lin-snow/ech0 >=0 <1.4.8-0.20260503040728-a7e8b8e84bd1)

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