CVE-2026-66307

Integer underflow (wrap or wraparound) in Skype for Business allows an unauthorized attacker to deny service over a network.

Scoring

Severity

HIGH

CVSS base score

7.5

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

EPSS probability

0.65%

CWE

CWE-191

Published

2026-09-08

Last modified

2026-09-11

Affected products

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

Weakness type

• CWE-191

Related vulnerabilities

• CVE-2026-81977 — Acrobat Reader | Integer Underflow (Wrap or Wraparound) (CWE-191)
• CVE-2026-78453 — Microsoft Windows SCSI Class System File Information Disclosure Vulnerability
• CVE-2026-77488 — Microsoft SQL Server Information Disclosure Vulnerability
• CVE-2026-71352 — Windows Remote Access Connection Manager Remote Code Execution Vulnerability
• CVE-2026-69824 — Microsoft Standard XPS Remote Code Execution Vulnerability
• CVE-2026-69687 — Windows USB Audio Class driver (usbaudio.sys) Elevation of Privilege Vulnerability
• CVE-2026-69421 — Windows Kernel-Mode Driver Elevation of Privilege Vulnerability
• CVE-2026-69303 — Push Message Routing Service Information Disclosure Vulnerability

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