Security & Threat Intelligence · 17.08.2026, 14:40 UTC
Apple Screen Sharing Security, (Mon, Aug 17th)
| Schweregrad | info |
|---|---|
| Kategorie | Security & Threat Intelligence |
| Quelle | SANS Internet Storm Center ↗ |
| Veröffentlicht | 17.08.2026 UTC |
Sicherheitsmeldung mit Schweregrad noch nicht bewertet. Technische Details im Tab „Originaltext“; empfohlene Schritte in der Checkliste.
About 20 years ago, with macOS 10.5 (Leopard), Apple introduced screen sharing. Apple did not invent a new protocol for screen sharing. Instead, it used the established VNC protocol. VNC is a pretty simple, unencrypted protocol using TCP port 5900. Historically, the protocol used a simple global password for authentication. Apple adapted the protocol for its own use, but overall, left the VNC protocol itself alone.
A couple of weeks ago, two severe vulnerabilities exposed issues Apple introduced when it bolted on its own modifications to VNC. Currently, these vulnerabilities are being exploited, and a system with screen sharing exposed should be considered compromised. But here are some tips to improve screen sharing security.
One weakness exposed by these recent vulnerabilities is Apple's support for both "regular" VNC authentication and authentication via Apple's own macOS authentication system.
Apple does allow old-fashioned VNC authentication by defining a VNC password. If this authentication scheme is used, a VNC client is prompted only for a password, not a username. The client may then ask for permission to use the screen, or they will be presented with an OS login prompt. This can be useful if you are trying to provide remote support to a logged-in user. But it does provide access to the system without any strong authentication. Access should still be secured by local user credentials, but the process already runs with elevated privileges to allow access for any user who logs in. This contributed to a recent vulnerability.
Next, you can restrict which users …