Missing Authorization in MCP Gateway - #VU139378
Published: July 26, 2026
Vulnerability identifier: #VU139378
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-862
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to disclose sensitive information.
The vulnerability exists due to missing authorization in tool aggregation across backend servers when resolving tool names from multiple aggregated servers without per-server scoping or collision checks. A local user can register a colliding tool name on an untrusted aggregated server to disclose sensitive information.
Exploitation requires the gateway to aggregate an untrusted server alongside a trusted one without a per-server tool-name prefix configured. Subsequent calls and their arguments may be silently dispatched to the shadowing server.
Affected software
MCP Gateway
Remediation
Install security update from vendor's website.
MCP Gateway - update to 0.43.1