CVE-2026-50517: CRITICAL deserialization flaw (CVSS 9.9) in Microsoft 365 Copilot permits remote code execution by authorized attackers. Microsoft has issued a server-side fix — confirm your environment is protected. https://radar.offseq.com/threat/cve-2026-50517-cwe-502-deserialization-of-untrusted-data-in-microsoft-microsoft-365-copilot-71d778a5726cf6f5 #OffSeq #Microsoft365 #CloudSecurity #CVE202650517