Toronto seller Matt Robb says a standing Facebook Marketplace message setting let Meta's Muse arrange a keyboard pickup at his building in late September without his knowledge.
Robb was away when the buyer arrived, but Muse's reply suggested he was home. The Guardian, which reviewed messages from the exchange, reported that the buyer waited outside for about 20 minutes before leaving without the keyboard.
Robb had given Muse his building's address as a pickup location while asking the AI agent to handle inquiries about the keyboard. He chose “Allow Always” for Marketplace messages, so replies could go out without a fresh prompt each time.
Robb said he thought Muse would ask again before accepting an offer or arranging a visit. After examining the activity with Meta, he said he learned that the ongoing permission covered a reply template containing the address. He had expected permission to answer inquiries to be separate from approval for a buyer to come to his building.
Meta says closing the app does not stop Muse from working. The agent can use a browser, fill out forms and negotiate for users, while its controls let them manage permissions and review its actions. Meta describes separate checks for some steps, including sending email and making purchases. In this exchange, Muse already had permission to send Marketplace replies.
David Singleton, an executive at Meta Superintelligence Labs, said Meta's review found “no breach of privacy controls.” Robb said his concern was what the standing permission allowed: the agent could share his address and set up an in-person pickup without asking him to confirm that plan. The buyer's trip ended without a handoff because Robb was away.
Meta intends to make the Marketplace permission prompt clearer, according to Robb.
