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Microsoft Security Response CenterCVE-2026-55007

Microsoft Exchange Server Remote Code Execution Vulnerability

HighVendor CVSS 8.1 / 10 1 CVE Published Sep 8, 2026 at 7:00 AM UTC

Summary

Double free in Microsoft Exchange Server allows an unauthorized attacker to execute code over a network.

Products covered

  • Microsoft Exchange Server 2019 Cumulative Update 14

  • Microsoft Exchange Server 2019 Cumulative Update 15

  • Microsoft Exchange Server Subscription Edition RTM

Remediation

Install KB5121610. Install KB5121609. Install KB5121608.

Vendor-listed fixes

  • 15.02.1544.046

  • 15.02.1748.051

  • 15.02.2562.049

CVEs in this advisory 1

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.