Skype for Business Spoofing Vulnerability
Published September 8, 2026Updated September 8, 2026
Source data
Overview
Improper verification of cryptographic signature in Skype for Business allows an unauthorized attacker to perform spoofing over an adjacent network.
Impact & technical details
Spoofing
How could an attacker exploit this vulnerability? An attacker with access to the internal network and a certificate trusted by the deployment could exploit this vulnerability by impersonating a trusted Skype for Business server. Successful exploitation could allow the attacker to act as another user or administrator without Skype credentials or user interaction.
- CVSS base score
- 8.3 / 10
- CVSS vector
- CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C
Highest base score supplied by MSRC for this record; the vector belongs to that score. Ratings can vary by product. Microsoft Important is displayed as High; Moderate is displayed as Medium.
Affected products
- Skype for Business Server 2015 CU13
- Skype for Business Server 2019 CU8
- Skype for Business Server Subscription Edition CU1
Source guidance
Remediation
The source provides update references without a separate remediation summary. Review the applicable update links below.
At least one Microsoft vendor-fix reference is available. Check each affected product for its applicable update, prerequisites, and supported version.
GTP recommendation · Rule-based guidance
Recommended next step
Review affected Microsoft products and apply the applicable security updates through your organization's normal patch-management process. Confirm availability and prerequisites in the Microsoft advisory.
Authoritative sources & updates
Findings and update information come from the linked publishers. GTP compiles the public record and provides the recommendation above. CVSS ratings shown here come from Microsoft. NVD references provide additional public context.
Managed by GTP?
Griffin Technology Partners managed customers may receive additional environment-specific security guidance and remediation assistance through their managed services relationship.
Security bulletins are provided for informational purposes and compiled from authoritative public sources. Vulnerability applicability varies by environment. Validate affected products, configuration, compatibility requirements, and vendor guidance before making production changes.