One Malicious GitHub Issue Was All It Took to Hijack a Claude Code Agent
A security researcher demonstrated a vulnerability in the Claude Code GitHub Action, allowing an attacker to hijack an agent's workflow with a single malicious GitHub Issue. This attack, a form of indirect prompt injection, exploited the agent's trust in external text inputs without needing stolen tokens or compromised runners. Standard defenses like input validation and system prompt hardening were insufficient, highlighting the need for an out-of-band inspection layer like Sentinel to distinguish between legitimate instructions and adversarial content. AI
IMPACT Highlights critical security risks in AI agents processing external inputs, necessitating robust validation beyond standard methods.