M365 Copilot Information Disclosure Vulnerability

Date Jun 9, 2026

Type Patch Tuesday

Signal Critical vendor advisory

Vendor / Product Microsoft · M365 Copilot

CVE CVE-2026-54130

Critical vendor advisory CVE-2026-54130

Summary

Missing authentication for critical function in M365 Copilot allows an unauthorized attacker to disclose information over a network. Published in June 2026 Security Updates. MSRC exploitability: Publicly Disclosed:No;Exploited:No;Latest Software Release:N/A.

Why it matters

Microsoft published this item through its Security Update Guide, making it part of Patch Tuesday triage for affected Windows, cloud, or application estates. EPSS percentile: 39%.

Operator check

Review the Microsoft Security Update Guide entry for CVE-2026-54130. Confirm whether M365 Copilot is deployed, then apply the current security update or documented mitigation. CVSS score: 9.8. EPSS probability: 0.5%; percentile: 39%.

Sources

MSRC 2026-Jun Security Update Guide NVD — CVE-2026-54130

PatchBrief uses public sources. It does not scan environments, verify exposure, or replace vendor guidance.

Get watched-vendor alerts Subscribe free Back to feed