CVE-2026-66305
Skype for Business Spoofing Vulnerability
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Skype for Business Spoofing Vulnerability
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
- Record
CVE-2026-66305- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N/E:U/RL:O/RC:C - Weakness
- CWE-603
- Updated
- 2026-11-02
EUVDEUVD-2026-73937
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
- Record
EUVD-2026-73937- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N/E:U/RL:O/RC:C - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-9823-h4m8-w7cq
Use of client-side authentication in Skype for Business allows an authorized attacker to perform...
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
- Record
GHSA-9823-h4m8-w7cq- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N - Weakness
- CWE-603
- Updated
- 2026-11-02
NVD
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
- Record
CVE-2026-66305- CVSS 3.1
- 7.1 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N - Weakness
- CWE-603
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-66305 is a high vulnerability (CVSS 7.1) in Microsoft Skype For Business Server 2015 Cu13, published September 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.53%, the 44th percentile. No source names a fixed version.