MCP Connect has unauthenticated remote OS command execution via /bridge endpoint

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary When AUTHTOKEN and ACCESSTOKEN environment variables are not set (which is the default out-of-the-box configuration) the /bridge HTTP endpoint is completely unauthenticated. Any network-accessible caller can POST a request with an attacker-controlled serverPath and args payload, causing the server to spawn an arbitrary OS process as the user running mcp-bridge. This results in full remote code execution on the host without any credentials. Details Root cause 1 - Authentication not enforced when token is absent src/config/config.ts line 161 sets authToken to an empty string when neither environment variable is configured: The auth middleware in src/server/http-server.ts lines 118–141 wraps all enforcement in if (this.accessToken). Because an empty string is falsy in JavaScript, the entire block is skipped and next() is called unconditionally for every request: The only consequence of a missing token is a log warning (line 42–43). The server starts and serves requests normally.…

Published by the source

19 Mar 2026, 12:51 UTC

Last modified by the source

19 Mar 2026, 13:01 UTC

Source last checked

26 Oct 2026, 12:46 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-wvr4-3wq4-gpc5

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-wvr4-3wq4-gpc5

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-wvr4-3wq4-gpc5

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# Patch Next advisory brief: GHSA-wvr4-3wq4-gpc5

Advisory: MCP Connect has unauthenticated remote OS command execution via /bridge endpoint
IDs: GHSA-wvr4-3wq4-gpc5
Record: https://patchnext.com/advisories/ghsa-wvr4-3wq4-gpc5 (revision 3, source checked 26 Oct 2026, 12:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm mcp-bridge: affected <= 2.0.0

## Suggested inspection (read-only)
- `npm ls mcp-bridge --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mcp-bridge.
- 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-wvr4-3wq4-gpc5 (GitHub-reviewed advisory GHSA-wvr4-3wq4-gpc5 lists affected ranges: npm mcp-bridge >=0 <=2.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-wvr4-3wq4-gpc5 (OSV record GHSA-wvr4-3wq4-gpc5 lists affected ranges: npm mcp-bridge >=0 <=2.0.0)

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