What is CVE-2026-54130?

CVE-2026-54130 is a critical-severity vulnerability in Microsoft 365 Copilot, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-06-18.

How severe is CVE-2026-54130?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Microsoft 365 Copilot

CVE-2026-54130

Missing authentication for critical function in M365 Copilot allows an unauthorized attacker to disclose information over a network.

Vulnerability class: Broken Authentication

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Microsoft 365 Copilot

Weakness classification (CWE)

CWE-306 — Missing Authentication for Critical Function

References

secure@microsoft.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-54130?: CVE-2026-54130 is a critical-severity vulnerability in Microsoft 365 Copilot, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-06-18.
How severe is CVE-2026-54130?: Critical severity. CVSS v3 base score is 9.8 out of 10.