Ech0: Scoped admin access tokens can bypass least-privilege controls on privileged endpoints, including backup export

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary Ech0 scoped access tokens do not reliably enforce least privilege: multiple privileged admin routes omit scope checks, and the backup export handler strips token scope metadata entirely, allowing a low-scope admin access token to reach broader admin functionality than intended. Impact An attacker who obtains a deliberately limited access token for an admin account can use that token to access privileged functionality outside its assigned scope. Confirmed impact includes access to /api/inbox with a token scoped only for echo:read and successful backup export via /api/backup/export?token=..., which returns a full ZIP archive. In practice, this turns a narrowly delegated API token into a broader privileged access and data exfiltration primitive. Details The issue is caused by a split authorization model: - JWTAuthMiddleware() authenticates the token and stores scope metadata in the viewer context - RequireScopes(...) enforces least privilege, but only when a route explicitly…

Published by the source

10 Apr 2026, 19:39 UTC

Last modified by the source

2 Jun 2026, 11:30 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4h9q-p5j4-xvvh

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# Patch Next advisory brief: GHSA-4h9q-p5j4-xvvh

Advisory: Ech0: Scoped admin access tokens can bypass least-privilege controls on privileged endpoints, including backup export
IDs: GHSA-4h9q-p5j4-xvvh
Record: https://patchnext.com/advisories/ghsa-4h9q-p5j4-xvvh (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.6)
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 4.3.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/lin-snow/ech0: affected < 4.3.5; fixed in 4.3.5

## 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-4h9q-p5j4-xvvh (GitHub-reviewed advisory GHSA-4h9q-p5j4-xvvh lists affected ranges: Go github.com/lin-snow/ech0 >=0 <4.3.5)

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