Cisco Systems Inc.’s WebEx Browser Extension has been found to have a critical vulnerability that allows hackers to gain access to a user’s computer via a remote code execution attack.

The vulnerability allows websites containing malicious scripts to open a WebEx session to the browser and “to execute arbitrary code on the affected system, which could be used to conduct further attacks.”

The vulnerability is said to be stem from a design defect in an application programming interface response parser within the plugin that allows an attacker to persuade an affected user to visit an attacker-controlled web page or follow an attacker-supplied link with an affected browser could exploit the vulnerability.

Google Project Zero researcher Tavis Ormandy, who was the first to discover the vulnerability, wrote on a Chromium bug tracking page that “there is not necessarily any user-visible indication of what is happening, visiting any website would be enough.”

Cisco said in a security advisory that the vulnerability does not affect Mac of Linux users and is limited to Windows users running the WebEx extension in Chrome, Firefox, and Internet Explorer. The company said it was in the process of patching the problem but currently there is no workaround available.

If you have the WebEx plugin installed, it’s advised that you remove it by using a tool available here. In the event that you need to join a WebEx meeting, it’s safe to do so via Microsoft’s Edge browser, which is not affected by the vulnerability.

Image credit: ooscarr/Flickr/CC by 2.0