Apple just patched a critical macOS flaw that let hackers break in without a password

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A hot potato: While traditionally a massive problem for Windows machines, zero-day flaws can wreak havoc on macOS as well. A newly disclosed vulnerability is about as dangerous as it gets, which is why Cupertino quickly fixed the issue on three different releases of its Mac operating system.

The Netherlands' National Cyber Security Centre (NCSC-NL) recently published an alarming security advisory about the new macOS flaw. It describes a vulnerability tied to an improper authentication process in Apple's line of desktop operating systems, which can have dire consequences on Mac systems when they have the built-in Screen Sharing feature turned on.

The vulnerability is tracked as CVE-2026-65400 and was assigned a CVSS score of 9.8. The CVSS system has a maximum severity of 10, which means CVE-2026-65400 is a highly dangerous flaw that should be patched as soon as possible.