Microsoft Copilot Hit by One-Click Data Theft Bug: A Single Link Could Leak Emails and MFA Codes
You thought your AI assistant was organizing your inbox. A hacker could be using it to organize your inbox for themselves.
Three key facts
CVE-2026-42824, codename SearchLeak. On June 15, Varonis Threat Labs publicly disclosed a three-stage attack chain targeting Microsoft 365 Copilot Enterprise Search. The exploit combines a parameter-to-prompt injection, an HTML rendering race condition, and a content-security-policy bypass via Bing server-side request forgery (SSRF). A victim only needs to click one crafted link — Copilot then automatically searches for and exfiltrates the user's emails, MFA two-factor codes, calendar entries, and SharePoint documents. Because the link uses a legitimate microsoft.com domain, standard URL filtering and anti-phishing tools are virtually powerless to flag it.
Microsoft patched it, but a CVSS scoring gap raises eyebrows. Microsoft's own advisory rates the vulnerability at CVSS 6.5; the National Vulnerability Database rates it 7.5. Microsoft says the fix has been automatically deployed and no user action is needed. The root issue: Copilot has full access to a user's mailbox, files, and calendar — a design choice made to enable "smarter answers" that also creates an unprecedented attack surface.
This is not Copilot's first security incident. Researchers demonstrated prompt injection attacks against Copilot as early as 2024–2025, but SearchLeak is the first complete chain that achieves one-click data exfiltration. Varonis's report points out that enterprises deploying AI assistants tend to focus on capabilities while ignoring attack surface — whatever data you let the AI see, an attacker can steal.
WangDou's Take
Microsoft's Copilot pitch goes: "Let AI read all your emails, files, and calendars so you can work more efficiently." Translate that into security-speak and you get: a full-data-access interface that can be remotely hijacked with a single link. The 6.5 vs. 7.5 CVSS gap shows that even Microsoft is playing "severity management." The most ironic part? The attack chain uses a microsoft.com domain — it's like a burglar walking through your front door with your own keys while the doorman salutes. Enterprises are paying a premium for Copilot to boost productivity, and it turns out the first thing that got boosted was the efficiency of getting hacked.
Source: BleepingComputer — New attack turned Microsoft 365 Copilot into 1-click data theft tool