CVE-2026-66302

Skype for Business Remote Code Execution Vulnerability

CVE-2026-66302 is fixed in 3 products on 1 platform, first by KB5123301, released September 8, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

Urgent

CVSS

9.8

Critical

Exploitation

None reported

Exploitation Less Likely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0097

62nd percentile

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

Where it's fixed

Product	Fix	Released
Microsoft
Skype for Business Server 2015 CU13	KB5123301	Sep 8, 2026
Skype for Business Server 2019 CU8	KB5123287	Sep 8, 2026
Skype for Business Server Subscription Edition CU1	KB5123300	Sep 8, 2026

Details

Published
September 8, 2026
Weakness
External Control of File Name or Path
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66302

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