This vulnerability (CVE-2026-65400) affects the Screen Sharing feature in Apple macOS, where an attacker on the same network might bypass authentication mechanisms and gain access without valid credentials. The root cause was an authentication issue related to state management. Apple fixed the issue in specific macOS versions: Sequoia 15.7.9, Sonoma 14.8.9, and Tahoe 26.6.1. The CVSS 3.1 base score is 7.1, reflecting network attack vector, low attack complexity, low privileges required, no user interaction, unchanged scope, high confidentiality impact, low integrity impact, and no availability impact.

Successful exploitation allows an attacker on the network to authenticate to macOS Screen Sharing without valid credentials, potentially leading to unauthorized access to the affected system's screen sharing session. This compromises confidentiality significantly, with limited impact on integrity and no impact on availability. No known exploits are reported in the wild at this time.

Apple has released official fixes in macOS Sequoia 15.7.9, macOS Sonoma 14.8.9, and macOS Tahoe 26.6.1 that address this vulnerability through improved state management. Users and administrators should apply these updates promptly to remediate the issue. No additional mitigation guidance is provided or required beyond applying these official patches.