One-Click Microsoft 365 Copilot Flaw Could Have Let Attackers Steal Emails, Files, and MFA Codes
Jun 15, 2026
Vulnerability / Enterprise Security
A single click on a trusted Microsoft link could have let an attacker pull emails, calendar details, and indexed files out of Microsoft 365 Copilot Enterprise Search. Researchers at Varonis Threat Labs chained three bugs into a one-click exfiltration path they call SearchLeak . Because the link pointed to a real microsoft.com domain, traditional anti-phishing and URL filtering tools were unlikely to flag it. No prompt, no password, no second click. Microsoft assigned CVE-2026-42824 and marked it critical; the CVSS scores ran lower and disagreed, 6.5 from Microsoft and 7.5 from the National Vulnerability Database . The company mitigated the flaw on its backend, so customers have nothing to worry about, and Varonis presented a proof-of-concept, not observed exploitation. Three bugs, one click Microsoft's advisory describes the flaw as a command injection that can expose information over a network. In practice, SearchLeak stacks one AI-specific weakness on two old web bugs, ...