New York (CNN Business) WhatsApp has fixed a security bug that allowed hackers to take over the messaging app with a malicious GIF.

The hack could be triggered when a user opened a malicious GIF in their gallery. After the GIF was opened, the app's contents could have been exploited, revealing previous chat history.

Devices running Android 8.1 and 9 could have been susceptible to the hack. A researcher called Awakened discovered the vulnerability and wrote about it in a blog post last week.

Facebook FB WhatsApp, which is owned by, released a patch last month, though it said it's unlikely anyone was actually hacked using the technique Awakened revealed.

"We have no reason to believe this affected any users, though of course we are always working to provide the latest security features to our users," a WhatsApp spokesperson told CNN Business.

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