Vulnerability Intelligence Report
Skype for Business Spoofing Vulnerability
CVE-2026-66305
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
No Active Exploit Signals
CVSS Base Score
7.1
HIGH
Exploitability:2.9
Impact Score:4.3
EPSS Probability:0.30%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
—
Authentication
—
Weaponization
—
SSVC Action
—
Weaknesses (CWE)
CWE-603 ↗CWE-603: Use of Client-Side Authentication
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| Microsoft | Skype for Business Server 2015 CU13 | 9319.0 < 6.0.9319.885 (affected) |
| Microsoft | Skype for Business Server 2019 CU8 | 2046.0 < 7.0.2046.569 (affected) |
| Microsoft | Skype for Business Server Subscription Edition CU1 | 2046.0 < 7.0.2046.879 (affected) |
References & Technical Advisories
No reference links found.
Threat Intelligence Signals
EPSS Score
0.296%
GitHub Advisory
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | Microsoft Corporation · Vendor · USA |
| Reserved | 2026-07-24T18:06:51 |
| Published | 2026-09-08T18:32:29 |
| Patch Date | 2026-09-08 |
| Last Updated | 2026-09-23T22:33:32 |
Community Chatter & Buzz