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Microsoft Security Response CenterCVE-2026-66302

Skype for Business Remote Code Execution Vulnerability

Severity not listedVendor CVSS 9.8 / 10 1 CVE Published Sep 8, 2026 at 7:00 AM UTC

Summary

External control of file name or path in Skype for Business allows an unauthorized attacker to execute code over a network.

Products covered

A separate affected-products list was not included in the collected bulletin.

Remediation

Install KB5123300. Install KB5123287. Install KB5123301.

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: Skype for Business Server 2015 CU13, Skype for Business Server 2019 CU8, Skype for Business Server Subscription Edition CU1.
    • Removed fixed versions: 6.0.9319.885, 7.0.2046.569, 7.0.2046.879.

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.