WhatsApp said Friday it discovered an advanced cyberespionage effort that took advantage of a chain of security vulnerabilities in the app and Apple devices to hack them.

A researcher with Amnesty International said unidentified members of civic groups appeared to be among those impacted.

In a brief statement, the Meta Platforms-ownedcommunications service said it had patched the security vulnerability that allowed hackers to take advantage of a second vulnerability on Appledevices and hijack the machines. In a statement, WhatsApp said that fewer than 200 users worldwide had potentially been impacted.​