I tried to break my own MCP prompt-injection detector. One class of attack walks straight through - and it isn't a bug.
A security researcher has discovered a new class of prompt injection attacks that bypass existing detection methods. The attack involves embedding a seemingly benign "system note" within tool outputs, which reassures the AI model that the content has been scanned and cleared. This deceptive annotation, classified as "DATA" by local LLM classifiers, allows malicious instructions to pass through undetected. The researcher found that even larger models like Qwen2.5:14b were susceptible to this tactic, highlighting a fundamental challenge for current AI security defenses. AI
IMPACT This discovery highlights a significant vulnerability in AI agent security, potentially requiring new defense mechanisms beyond current signature and classification methods.