AI agent incident

A self-replicating prompt injection spread through Word documents via Copilot

Reported · 2 sources

What happened

Researcher Hakon Maloy disclosed hidden prompts in Word documents that made Microsoft Copilot rewrite figures in a report and copy the injection into new documents it produced. The issue had been reported to Microsoft 144 days earlier with no complete fix available.

Why it matters

Self-propagation means the injection outlives the document it arrived in and survives independent editing sessions, which is not something document-level data controls were built to stop.

Sources

  1. Simon Willison AI Worming through Word
  2. The Hacker News Microsoft Copilot for Word Can Copy Hidden Prompts Into New Documents

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Cite or correct this record

“A self-replicating prompt injection spread through Word documents via Copilot.” The Permission Layer AI Agent Incident Database, https://thepermissionlayer.com/incidents/copilot-word-prompt-injection-worm/. Database updated October 22, 2026.

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