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Leaked phone number reveals even Mark Zuckerberg is on Signal
August 09, 2025
It was revealed just a few days ago that phone numbers and other details belonging to 533 million Facebook users had leaked on a hacking forum. The trove of data may have been obtained via a 2019 vulnerability that has since been patched, and it turns out that Facebook co-founder Mark Zuckerberg’s phone number was leaked as well.
Now, security researcherDave Walker(h/t:India Today) has used Zuckerberg’s number to discover that he used theSignalmessaging app. Walker also posted a screenshot showing the Facebook co-founder’s purported contact on Signal. Check it out below.
It’s entirely possible the Facebook co-founder simply used Signal to check out the competition and for nothing more. But there’s also the obvious implication that Zuckerberg is actively using Signal as a messaging app because he prefers its security, features, and/or design. For what it’s worth, Walkersaysthe Signal account has been closed as of yesterday (April 5). Take that for what you will.
The researcher alsoseemed to suggestthat Zuckerberg wasn’t on Telegram. The app allows you to restrict who can find you on the service using your phone number though, so it’s still theoretically possible the Facebook co-founder is using the platform.
We contacted Facebook for comment regarding Zuckerberg’s Signal account (i.e. whether it was actively used and if he was still using WhatsApp). “This isn’t something we would comment on and have nothing further to add,” a company representative toldAndroid Authority.
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