CVE-2026-26133

Microsoft 365 Copilot is an AI assistant that can help people work with Microsoft documents and data. In this vulnerability, attackers can try to “trick” the AI into processing attacker-supplied instructions, which may cause confidential information to be revealed. Think of it like getting someone’s assistant to follow a malicious script instead of your request, causing private info to come back.

This matters if your business uses Microsoft 365 Copilot and the listed Microsoft apps (Edge, Excel, Loop, OneNote, Outlook, Power BI, PowerPoint, Teams, Word). It is network-reachable without needing an attacker account, but it also requires user interaction, so it’s most relevant to how employees use Copilot and what they click or open.

Based on the findings, treat this as a risk only in realistic scenarios where an attacker can reach your Copilot usage flow and trigger the needed user interaction.

This is AMBER because the issue can expose confidential information, and it’s described as an attacker-driven injection that retrieves data. While there’s no confirmed public exploit code on record and no KEV listing, Microsoft has provided fixed versions for multiple products, so updates should be prioritized.