CVE-2026-26137: Microsoft 365 Copilot Chat

Critical severity, CVSS 9.9. EPSS: 0.7% chance of exploitation in the next 30 days.

Server-side request forgery (ssrf) in Microsoft Exchange allows an authorized attacker to elevate privileges over a network.

Affected products

• Microsoft 365 Copilot Chat: affected versions not specified

Published 2026-03-19. Last modified 2026-06-17.