Remote code execution in a Microsoft core component (Microsoft Account) affects broadly deployed Windows systems and can enable widespread compromise.
CVE-2026-56165
Heap overflow in Microsoft Account enabling unauthenticated remote code execution.
Is CVE-2026-56165 being exploited?
Not confirmed. CVE-2026-56165 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 0.72% probability of exploitation in the next 30 days.
How severe is CVE-2026-56165?
CVE-2026-56165 is rated Critical with a CVSS score of 9.8. 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-2026-56165?
Yes. A fix has been recorded for CVE-2026-56165. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-56165 affect?
CVE-2026-56165 affects Microsoft Account (Windows component), Windows 10, Windows 11, Windows Server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-56165?
Implement network restrictions, monitor for exploitation, apply vendor patch immediately when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote code execution over network via heap-based buffer overflow; attacker can run arbitrary code as system-level user.
Immediate action required