Description
The mcp-router CLI served its MCP aggregator on every interface and enforced authentication only when the operator asked for it. The serve command in apps/cli/src/commands/serve.ts defaulted its host to the all-interfaces address on a fixed port, and required a token only when the corresponding flag was supplied, so a default invocation exposed the aggregator, and every MCP server it fronted, to anyone able to reach the port. Release 0.6.3 defaults the host to the loopback address and refuses to start without a token whenever the host it is given is not a loopback address; no earlier release carries either check.
Published: 2026-08-27
Score: 9.3 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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History

Fri, 28 Aug 2026 16:45:00 +0000

Type Values Removed Values Added
First Time appeared Mcp-router
Mcp-router mcp-router
Vendors & Products Mcp-router
Mcp-router mcp-router

Thu, 27 Aug 2026 18:00:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 27 Aug 2026 16:45:00 +0000

Type Values Removed Values Added
Description The mcp-router CLI served its MCP aggregator on every interface and enforced authentication only when the operator asked for it. The serve command in apps/cli/src/commands/serve.ts defaulted its host to the all-interfaces address on a fixed port, and required a token only when the corresponding flag was supplied, so a default invocation exposed the aggregator, and every MCP server it fronted, to anyone able to reach the port. Release 0.6.3 defaults the host to the loopback address and refuses to start without a token whenever the host it is given is not a loopback address; no earlier release carries either check.
Title mcp-router CLI before 0.6.3 Binds the MCP Aggregator to All Interfaces Without Requiring Authentication
Weaknesses CWE-306
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

Mcp-router Mcp-router
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-27T18:01:28.356Z

Reserved: 2026-08-26T16:00:31.661Z

Link: CVE-2026-81094

cve-icon Vulnrichment

Updated: 2026-08-27T18:01:25.435Z

cve-icon NVD

Status : Received

Published: 2026-08-27T17:20:51.650

Modified: 2026-08-27T20:18:49.427

Link: CVE-2026-81094

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-28T16:14:35Z

Weaknesses
  • CWE-306

    Missing Authentication for Critical Function