CVE-2026-66307CWE-191

CVE-2026-66307

High · published September 8, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
67.3
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.01174 · 67.3th percentile
Weakness
CWE-191 · Integer Underflow (Wrap or Wraparound)
Published
2026-09-08T23:18Z
Affected products (6)
ProductVersionsFixed in
microsoft/skype_for_business_serverall versions—
microsoft/skype_for_business_serverall versions—
microsoft/skype_for_business_serverall versions—
microsoft/skype_for_business_serverall versions—
microsoft/skype_for_business_serverall versions—
microsoft/skype_for_business_server_subscription_editionall versions—
References (1)
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66307 · [email protected]
EPSS history
Timeline
  • 10 SEP 03:17Z
    EPSS moved — → 1%
    epss
  • 08 SEP 18:39Z
    Skype for Business and Lync Denial of Service Vulnerability
    cvelistv5