Microsoft closed four Copilot command-injection flaws, one scored 9.9 for privilege escalation

What happened

Microsoft published four Copilot advisories on 17 September 2026. The most severe, CVE-2026-85885, is a command injection in Microsoft 365 Copilot that lets a signed-in attacker elevate privileges over the network with no user interaction, which Microsoft scores CVSS 3.1 9.9. The other three disclose information: CVE-2026-85887, an incorrect permission assignment in Microsoft 365 Copilot scored 7.7; CVE-2026-78501, a command injection in Business Chat scored 7.4; and CVE-2026-55946, a command injection in Microsoft Copilot scored 6.1.

All four are cloud-service advisories: Microsoft states each flaw is already fully mitigated in the service, with no action for users, and marks all four as unexploited at release. NVD's own analysis scores CVE-2026-85885 at 8.8, reading its scope as unchanged where Microsoft reads it as changed.