Researchers found 37 vulnerabilities in four common open-source VNC remote desktop applications that exist since 1999. These vulnerabilities allow attackers to compromise the targeted systems remotely.

According to Kaspersky’s analysis, more than 600,000 VNC servers accessed remotely over the Internet, based on the data collected using the Shodan search engine.

37 Vulnerabilities

37 vulnerability discovered with four VNC components that include ten in LibVNC, four in TightVNC 1.X, one in TurboVNC and 22 in UltraVNC.

The VNC applications are available in both free and commercial versions, they are compatible with operating systems like Windows, Linux, macOS, and Android.


VNC applications contain two components one to be deployed in the server and next with the client machine that used to access the server.

Kaspersky researchers found vulnerabilities in both the server and client components, linked to incorrect memory usage that leads to malfunctions and denial of service.

In some extensive cases, the vulnerabilities let attackers gain unauthorized access to the device or to deploy malware on the victim machine.

Following are the possible attack vectors

  • An attacker is on the same network with the VNC server and attacks it to gain the ability to execute code on the server with the server’s privileges.
  • A user connects to an attacker’s ‘server’ using a VNC client and the attacker exploits vulnerabilities in the client to attack the user and execute code on the user’s machine.

The bugs have been reported to the developers and most of them have been fixed already, except TightVNC 1.x which was no longer supported. Developers recommended using TightVNC 2.X versions.

Researchers recommended monitoring the remote access programs in your infrastructure, check the devices connecting remotely and recommend using strong passwords.

Do not establish a connection with untrusted or untested VNC servers and to use specialized security solutions for industrial automation systems.

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