Prompt Guard v2.5.1

Advanced prompt injection defense + operational security system for AI agents.

🚨 What's New in v2.5.1 (2026-01-31)

CRITICAL: System Prompt Mimicry Detection

Added detection for attacks that mimic LLM internal system prompts:

• <claude_*>, </claude_*> — Anthropic internal tag patterns
• <artifacts_info>, <antthinking>, <antartifact> — Claude artifact system
• [INST], <<SYS>>, <|im_start|> — LLaMA/GPT internal tokens
• GODMODE, DAN, JAILBREAK — Famous jailbreak keywords
• l33tspeak, unr3strict3d — Filter evasion via leetspeak

Real-world incident (2026-01-31): An attacker sent fake Claude system prompts in 3 consecutive messages, completely poisoning the session context and causing all subsequent responses to error. This patch detects and blocks such attacks at CRITICAL severity.

🆕 What's New in v2.5.0