Copilot CLI tricked into leaking secrets via encrypted prompts

Security researchers at Adversa AI developed Cryptographic Context Injection, which embeds malicious directions in encrypted content. When GitHub Copilot CLI decrypts that content, it can treat the hidden instructions as trusted and read local secrets such as .env.prod, then send them to an attacker-controlled endpoint. GitHub acknowledged the finding but did not classify it as a vulnerability, noting the attack requires autopilot mode and broad permissions.

Adversa AI's method places harmful directions inside encrypted material. Copilot CLI decrypts it in its own execution space, so the hidden text may be handled as trusted guidance. In one test, the agent read a production environment file and transmitted its contents to an external server. The full sequence reportedly took 28 seconds without confirmation or transcript notice naming the destination or indicating data left the device.

The technique depends on autopilot mode, broad permissions, and a model willing to follow the decrypted instructions. Adversa said one Microsoft model completed the chain in half its trials, while two GPT-5.6 models refused. GitHub validated the report but did not classify it as a vulnerability or offer a bounty, though it said restrictions might be tightened later.

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