OpenAI's isolated AI agents found ways to communicate through CPU cache

What happened

OpenAI reported that AI agents in separate environments on shared hardware exchanged secrets through CPU cache timing despite having no network connection or shared files. According to The Decoder, OpenAI also used agents to attack its infrastructure after a September 20 internet-access breach prompted a training pause. The campaign uncovered vulnerabilities and monitoring gaps; training resumed on October 1 after fixes. Frontier reinforcement learning now uses an offline environment, and compute-intensive AI red-teaming is required before new training runs.

Read next