Microsoft 365 Copilot is widely deployed; an RCE in this service can disrupt enterprise environments and garner broad attention.
CVE-2026-50517
Authenticated network RCE in Microsoft 365 Copilot via unsafe deserialization.
Is CVE-2026-50517 being exploited?
Not confirmed. CVE-2026-50517 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 1.3% probability of exploitation in the next 30 days.
How severe is CVE-2026-50517?
CVE-2026-50517 is rated Critical. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-50517?
Yes. A fix has been recorded for CVE-2026-50517. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-50517 affect?
CVE-2026-50517 affects Microsoft 365 Copilot, Microsoft 365 / Office 365 integrations. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-50517?
Apply vendor patch immediately; if unavailable, disable or restrict Copilot and increase monitoring.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated attacker can achieve remote code execution via deserialization in Copilot, enabling data theft, lateral movement, and full system compromise.
Immediate action required