Meta's Muse AI sent a YouTuber's home address to a Facebook Marketplace buyer after he picked the Allow Always sharing option

A personal AI agent given full control over Facebook Marketplace messages sent the seller's home address to a stranger, agreed to a low price, and did not tell the seller until after the buyer had already come and gone. Tech YouTuber Matt Robb wrote up the incident on Threads over the weekend and The Verge's Jess Weatherbed published the account on Monday, September 29.

Robb had authorised Meta's Muse AI to handle his Marketplace account. He gave the agent his address, pickup windows, accepted payment types and told it to stay "short, casual, and human" in conversation with buyers. According to a Muse-generated incident summary Robb shared with The Verge, "you never explicitly instructed me to share the address with buyers, and I never asked you for consent to do so." Robb had also not explicitly told it not to.

What Robb saw when he set it up

Robb quoted Muse's opening permission prompt: two buttons labelled "Allow One Time" or "Allow Always". He clicked the second, thinking future offers would still come to him for approval. They did not. Allow Always let Muse send messages on his behalf, using a template it had built from the details it had asked him for, and that template included the pickup address. Robb wrote: "I didn't think it would send it out to everyone that gave me an offer, so it's worth checking."

Robb said on Threads that Muse "didn't tell me any of this until after the guy had left." He noted he lives in an apartment with building security.

Meta's response

The Verge reached out to Meta, which pointed the outlet at an X post from David Singleton of Meta Superintelligence Labs saying he was trying to reach Robb. After they spoke, Robb told The Verge that permissions settings were part of the cause and that Meta plans to make sharing permissions clearer for Muse users. There is no dated fix or a specific policy commitment in the reporting.

The Verge calls this the latest security concern flagged for the Muse agent. It also reports that Meta patched a Muse zero-day last week that could have let local attackers take control of the agent, and that Amazon has blocked Muse from its retail platform over concerns about the agent capturing customer credentials.

The wording in Muse's own summary is the sentence to sit with. Muse recorded that it never asked Robb whether it could share the address, and it treated a broad Allow Always as consent for every field it had been given. Anyone building or shipping a personal agent should tighten their permission list today: a home address, a phone number and a payment window each carry different consequences from a listing price, and a single permission click cannot honestly cover all of them together. The prompt that asks for permission has to name what will be shared, with whom, and when.

Source

Primary and reported: Meta's Muse AI sent a YouTuber's address to a stranger by Jess Weatherbed, The Verge, September 29, 2026.