Detections
Analytics

MCP Server Authentication Bypass

high Web App Scanning Plugin ID 115226

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Synopsis

MCP Server Authentication Bypass

Description

Model Context Protocol (MCP) servers may expose tools, prompts and resources that require authentication to be accessed. An authentication bypass occurs when the MCP server does not properly enforce authentication on requests, allowing unauthenticated users to invoke tools, read prompts or access resources that should be restricted. This can lead to unauthorized access to sensitive data or actions on behalf of legitimate users.

This detection is included in the AI and LLM category.

Solution

Ensure that the MCP server properly enforces authentication on all endpoints exposing tools, prompts and resources. Review the authentication and authorization implementation to guarantee that unauthenticated requests are rejected and that access controls cannot be bypassed.

See Also

https://modelcontextprotocol.io/specification/2025-06-18/basic/authorization

Plugin Details

Severity: High

ID: 115226

Type: Check Based

Published: 4/30/2026

Updated: 4/30/2026

Scan Template: api, basic, full, mcp, pci, scan

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 7.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: Tenable

CVSS v3

Risk Factor: High

Base Score: 8.2

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

CVSS Score Source: Tenable

CVSS v4

Risk Factor: High

Base Score: 8.8

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS Score Source: Tenable

Reference Information