TL;DR 📌

• Apple macOS contains an improper authentication vulnerability that could allow an attacker on the network to authenticate to Screen Sharing without valid credentials.
• Highest CVSS: 9.8 (Critical).
• Listed in CISA KEV (2026-08-18) — this is being exploited in the wild.
• Check the advisory for fixed releases — remediation detail is in the vendor link below.
• CVEs: CVE-2026-65400.

What it is

CVE-2026-65400 is an improper authentication flaw in macOS Screen Sharing. The vulnerability allows an attacker on the network to authenticate to Screen Sharing without supplying valid credentials.