A2A Protocol -- Agent Card Poisoning Vulnerability
Date: 2026
Affected: A2A Protocol
Attack vector: prompt-injection
Category: real-world
Severity: Medium

Google's Agent-to-Agent (A2A) protocol has systemic vulnerabilities: agent card poisoning (malicious metadata injection causing data exfiltration), agent impersonation/shadowing, replay attacks, and contagion risk (one compromised agent influencing others in collaborative workflows). The spec delegates credential management entirely to implementers with no built-in protections.


Mitigations:

Architectural layers (MAESTRO):