Vulnerability · Published Sep 8, 2026 · Assigned by microsoft
CVE-2026-66305Skype for Business Spoofing Vulnerability
High 7.1
In plain English
A high-severity security flaw in Skype for Business Server 2015 CU13 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities).
Severity (CVSS 3.1)7.1High
Exploit odds (30 days)0.5%top 55.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Skype for Business Server 2015 CU13 | 9319.0 – before 6.0.9319.885 |
| Microsoft | Skype for Business Server 2019 CU8 | 2046.0 – before 7.0.2046.569 |
| Microsoft | Skype for Business Server Subscription Edition CU1 | 2046.0 – before 7.0.2046.879 |
Weakness: CWE-603 · Vector: 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
References
- Skype for Business Spoofing Vulnerability vendor-advisory, patch