CVE-2026-65400
Apple macOS Improper Authentication Vulnerability
Apple macOS
An authentication issue was addressed with improved state management. This issue is fixed in macOS Sequoia 15.7.9, macOS Sonoma 14.8.9, macOS Tahoe 26.6.1. An attacker on the network may be able to authenticate to Screen Sharing without valid credentials.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 18 August 2026. US federal agencies were required to remediate it by 21 August 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 10.5%, which is higher than 95.5% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2026-65400 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-65400.
What does CVE-2026-65400 affect?
CVE-2026-65400 affects Apple macOS. An authentication issue was addressed with improved state management. This issue is fixed in macOS Sequoia 15.7.9, macOS Sonoma 14.8.9, macOS Tahoe 26.6.1. An attacker on the network may be able to authenticate to Screen Sharing without valid credentials.
How severe is CVE-2026-65400?
CVE-2026-65400 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 10.5%, higher than 95.5% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 21 August 2026.
How should organisations respond to CVE-2026-65400?
Apply the vendor patch for Apple macOS as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.