PromptArmor says Claude AI can leak Excel files

PromptArmor disclosed on November 27, 2025 that Claude AI has an indirect prompt injection attack that can be triggered by Excel files, causing file data leakage. PromptArmor provided a link to the full attack chain in a tweet and mentioned that it published a related report in The Information. The same disclosure also stated that Anthropic has promptly taken mitigation measures. Currently, the incident has no further evidenced developments, and the status remains at PromptArmor's disclosure and the claim that Anthropic has mitigated it.

AI-generated from public reports

1. Report date Nov 27· 2 reports

   PromptArmor says Claude AI can leak Excel files

   Source:PromptArmor