Main Vulnerability Database Vulnerabilities #VU148355

Integer underflow in Skype for Business Server and Skype for Business Server Subscription Edition - CVE-2026-66307

Published: September 9, 2026

Vulnerability identifier: #VU148355

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-66307

CWE-ID: CWE-191

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to integer underflow in Skype for Business and Lync. A remote attacker can trigger integer underflow and cause a denial of service condition on the target system.

Affected software

Skype for Business Server
Skype for Business Server Subscription Edition

How to mitigate CVE-2026-66307

Install updates from vendor's website.

Skype for Business Server - addressed in versions 6.0.9319.885, 7.0.2046.569
Skype for Business Server Subscription Edition - update to 7.0.2046.879

External References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307

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