CVE-2026-81094CWE-306

CVE-2026-81094

Critical · published August 27, 2026

CVSS v3.1
9.1
EPSS
1%
Percentile
48.5
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
9.3 · 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
EPSS
0.00609 · 48.5th percentile
Weakness
CWE-306 · Missing Authentication for Critical Function
Published
2026-08-27T21:20Z
References (5)
EPSS history
Timeline
  • 27 AUG 14:50Z
    mcp-router CLI before 0.6.3 Binds the MCP Aggregator to All Interfaces Without Requiring Authentication
    cvelistv5