CVE intelligence

CVE-2026-66303

Vulnerability intelligence

Published Sep 8, 2026Sources checked Oct 28, 2026

6.5MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2026-66303 and is rated Medium severity with a CVSS score of 6.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Sep 8, 2026

Install KB5123301. Install KB5123300. Install KB5123287.

Vendor-listed releases

6.0.9319.885
7.0.2046.569
7.0.2046.879

CISA KEVNot listedBased on the latest collected catalog

EPSS1.1%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-66303?

Null pointer dereference in Skype for Business allows an authorized attacker to deny service over a network.

Source: NVD