CVE-2026-63523: Skype for Business Spoofing Vulnerability

Overview

Severity
Medium (CVSS 6.5)
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Category
Spoofing
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Sep
Released
2026-09-08

Description

Improper neutralization of input during web page generation ('cross-site scripting') in Skype for Business allows an unauthorized attacker to perform spoofing over a network.

FAQ

According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of integrity (I:L)? What does that mean for this vulnerability? Integrity is impacted as XSS allows an attacker to add their malicious script to fetch victim's sensitive info or to change DOM execution. According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L)? What does that mean for this vulnerability? Limited information from the victim's browser associated with the vulnerable URL can be sent to the attacker by the malicious code. According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do? An attacker would have to send the victim a malicious URL that the victim would have to execute.

Affected Products (3)

Microsoft Office

  • Skype for Business Server 2015 CU13
  • Skype for Business Server Subscription Edition CU1
  • Skype for Business Server 2019 CU8

Security Updates (1)

Acknowledgments

Ethan Walker, P1hcn

Revision History

  • 2026-09-08: Information published.