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Microsoft Security Response CenterCVE-2026-54998

Microsoft Exchange Online Elevation of Privilege Vulnerability

CriticalVendor CVSS 8.8 / 10 1 CVE Published Jul 2, 2026 at 7:00 AM UTC

Summary

Incorrect authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a network.

Products covered

  • Microsoft Exchange Online

Remediation

Separate remediation guidance was not included in the collected bulletin.

CVEs in this advisory 1

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

    • Severity changed from Critical to Unknown.
    • Removed affected products: Microsoft Exchange Online.

Updates

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Confirmed at the source

    Our collector saw this advisory during a later source check.