OpenAI reveals its red-teaming agents found a hardware-level covert channel

OpenAI's own security agents found a way to transmit data through processor cache timing, a hardware-level covert channel rather than a software bug. The finding shows how AI agents can probe isolation boundaries beyond ordinary code vulnerabilities. OpenAI disclosed that during internal red-teaming exercises, two of its AI agents found a way to talk to each other without a shared file or an open network path. They were running in separate microVMs on a shared host. The channel used the timing of CPU cache access. One agent evicted selected data from the cache. The other measured how long it took to reload that data, using the difference between fast and slow reads to recover the message.