MCP Server Top 10 Security Risks

As AI systems become increasingly integrated into software supply chains, enterprise applications, and security infrastructure, the Model Context Protocol (MCP) is emerging as a critical framework for AI-to-tool connectivity. However, with the power and flexibility of MCP comes a new class of vulnerabilities and attack surfaces that organizations must understand and address.

This Top 10 list outlines the most critical security concerns in MCP server implementations, spanning from prompt injection and tool poisoning to credential exposure and insecure configurations. These risks are amplified in scenarios involving agentic AI, model chaining, multi-modal orchestration, and dynamic role assignment.

The Top 10 MCP Server Security Risks

MCP-01: Prompt Injection

The manipulation of MCP server behavior through malicious prompts

Prompt injection attacks occur when malicious prompts manipulate MCP server behavior or bypass security controls. This includes direct injection through user input, indirect injection through data sources, and manipulation of tool descriptions. These attacks can lead to unauthorized actions, data exfiltration, and privilege escalation, making this the most critical MCP security risk.

Impact: Unauthorized actions, data exfiltration, privilege escalation

MCP-02: Confused Deputy

MCP servers performing actions with incorrect permissions or on behalf of the wrong user

The confused deputy problem occurs when MCP servers perform actions on behalf of the wrong user or with incorrect permissions. This can result in authorization bypass, cross-user data access, and privilege escalation. The complexity of MCP’s role-based interactions makes this vulnerability particularly dangerous in multi-user environments.

Impact: Unauthorized access, data breaches, system compromise

MCP-03: Tool Poisoning

Malicious tools masquerading as legitimate ones or legitimate tools with malicious descriptions

Tool poisoning involves malicious tools masquerading as legitimate ones, or legitimate tools with malicious descriptions designed to trick AI models. Examples include fake tool descriptions, malicious tool implementations, and tool name squatting. This attack vector exploits the trust relationship between AI models and their available tools.

Impact: Malicious code execution, data theft, system compromise

MCP-04: Credential and Token Exposure

Improper handling, storage, or transmission of API keys, OAuth tokens, and other credentials

Credential and token exposure occurs through improper handling, storage, or transmission of API keys, OAuth tokens, and other sensitive credentials. This includes hardcoded credentials, token theft, and credential leakage in logs. Given MCP’s reliance on API integrations, credential security is fundamental to overall system security.

Impact: Account takeover, unauthorized API access, data breaches

MCP-05: Insecure Server Configuration

Weak default configurations, exposed endpoints, and inadequate authentication

Insecure server configuration encompasses weak default configurations, exposed endpoints, and inadequate authentication mechanisms. This includes default credentials, open endpoints, and weak authentication systems. Many MCP security incidents stem from basic configuration errors that leave systems vulnerable.

Impact: Unauthorized access, data exposure, system compromise

MCP-06: Supply Chain Attacks

Compromised MCP servers, malicious dependencies, or rug pull attacks

Supply chain attacks target the MCP ecosystem through compromised MCP servers, malicious dependencies, or rug pull attacks where maintainers abandon or maliciously modify previously trusted servers. The distributed nature of MCP server development makes supply chain security particularly challenging.

Impact: Widespread compromise, data theft, service disruption

MCP-07: Excessive Permissions and Scope Creep

MCP servers requesting more permissions than necessary or escalating privileges

Excessive permissions occur when MCP servers request more permissions than necessary for their intended function, or when privileges gradually escalate over time. This includes overprivileged OAuth scopes, unnecessary file system access, and excessive API permissions that increase the potential impact of a compromise.

Impact: Increased attack surface, potential for greater damage if compromised

MCP-08: Data Exfiltration

Unauthorized access to or transmission of sensitive data through MCP channels

Data exfiltration involves unauthorized access to or transmission of sensitive data through MCP channels. This can occur through sensitive data in responses, covert channels, or unauthorized data access. The ability of MCP servers to access diverse data sources makes this a significant concern for data protection.

Impact: Data breaches, privacy violations, regulatory non-compliance

MCP-09: Context Spoofing and Manipulation

Manipulation of context information provided to models to alter behavior

Context spoofing involves manipulation of context information provided to AI models to alter their behavior in unintended ways. This includes fake context injection, context poisoning, and state manipulation. These attacks exploit the AI model’s reliance on context to make decisions about tool usage.

Impact: Incorrect model behavior, unauthorized actions, security bypass

MCP-10: Insecure Communication

Unencrypted or improperly secured communication channels

Insecure communication encompasses unencrypted or improperly secured communication channels between MCP components. This includes unencrypted transport, weak TLS implementation, and vulnerability to man-in-the-middle attacks. Secure communication is fundamental to preventing interception of sensitive data and credentials.

Impact: Data interception, credential theft, communication tampering

Honourable Mentions

While not in the top 10, these additional security concerns are important for comprehensive MCP security:

Insufficient Logging and Monitoring

Inadequate logging of MCP operations, missing audit trails, and poor security monitoring make it difficult to detect attacks, respond to incidents, and maintain compliance.

Resource Exhaustion (DoS)

MCP servers vulnerable to resource exhaustion attacks through memory exhaustion, compute resource abuse, or rate limiting bypass, affecting system availability.

Input Validation Failures

Inadequate validation and sanitization of inputs to MCP tools and resources, leading to classic injection attacks like SQL injection or command injection.

Session Management Failures

Weak session handling, session hijacking, and inadequate session termination that can lead to unauthorized access and privilege escalation.

Improper CORS configuration allowing unauthorized cross-origin access, particularly relevant for web-based MCP implementations.

Protocol Downgrade Attacks

Forcing connections to use weaker security protocols or versions, compromising the security of MCP communications.

Dependency Confusion

Attackers creating malicious packages with similar names to legitimate MCP servers, exploiting package management systems.

Using This Guide

This Top 10 list serves as a foundation for understanding MCP security risks. Each risk will be expanded into detailed guidance covering:

Detailed attack scenarios and real-world examples
Technical implementation of attacks and defenses
Prevention strategies and secure coding practices
Detection and monitoring approaches
Incident response procedures

Organizations should use this list to assess their MCP implementations, prioritize security investments, and develop comprehensive security strategies for AI-integrated systems.