One-Click Microsoft 365 Copilot Flaw Could Have Let Attackers Steal Emails, Files, and MFA Codes
Summary: Researchers at Varonis Threat Labs chained three bugs into a one-click exfiltration path called SearchLeak that could pull emails, calendar details, and indexed files out of Microsoft 365 Copilot Enterprise Search, assigned CVE-2026-42824 and rated critical. The chain uses Parameter-to-Prompt injection in the q parameter of the Copilot Enterprise Search URL, a race condition where an injected image tag fires before Microsoft's code-block sanitizer runs, and a Bing image-fetch endpoint allowlisted by the page's Content Security Policy to carry stolen data out.
Bottom line: Copilot Enterprise reaches whatever the signed-in user can through Microsoft Graph, so an attacker inherits that reach without logging in - and the most time-sensitive prize is the inbox, where MFA codes and password-reset links stay valid for only a few minutes. Because Copilot Enterprise is a managed service, tenant admins cannot patch the parts that failed; they can only watch for encoded payloads in the q parameter and unusual outbound requests to Bing's image endpoints.
Read the original at The Hacker News ↗
- Topics
- Vulnerabilities & Patching
- Mentions
- CVE-2025-32711CVE-2026-42824
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