One-Click Microsoft 365 Copilot Flaw Could Have Let Attackers Steal Emails, Files, and MFA Codes

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

The report describes SearchLeak, a three-bug chain in Microsoft 365 Copilot Enterprise that could let an attacker exfiltrate emails, calendar details, MFA codes, and indexed files through a single crafted Microsoft link. Varonis and other coverage say Microsoft remediated the issue as a critical vulnerability, assigned CVE-2026-42824, and the attack relied on parameter-to-prompt injection, an HTML rendering race condition, and an SSRF-based CSP bypass. CyberSE.AI analysis: this is primarily a data leakage risk because the core impact is unauthorized disclosure from connected enterprise content, so organizations should review AI search trust boundaries, output sanitization, and allowlisted fetch paths in Copilot-style integrations.