Vulnerability / research

ShareLeak let form submissions redirect Copilot Studio agents

Reported

What happened

Capsule demonstrated indirect prompt injection in SharePoint form submissions that redirected a Copilot Studio agent to send connected customer information to an external email address.

Parties and reporting

AI tools and systems: Microsoft Copilot Studio, SharePoint, CVE-2026-21520

Outcome

Capsule reported a January fix. Microsoft's CVE record describes unauthenticated sensitive-information disclosure.

Operating lesson

Separate external form content from agent authority and constrain where connected data can be sent.

Evidence and limits

Date follows Microsoft's January 22 public-disclosure field. Capsule instead dates CVE publication January 15; detailed research appeared April 15. No malicious exploitation is established.

Sources