Meta disables Muse sharing after researchers find searchable links to sensitive chats

Meta has switched off Muse’s conversation-sharing feature after security researchers found links exposing sensitive personal and business information. The company told Ars Technica it had disabled sharing, according to Futurism’s October 20 coverage. Researchers at security firm Claroc said they identified 6,800 share links through a search of historical domain records, then examined several hundred.

The address itself supplied the clues

Muse let users create web links to share conversations and other content. Anyone with a link could open the page it pointed to. Such sharing systems typically use a long, hard-to-guess sequence of characters to keep people who were not given the address from finding it.

Muse’s links also contained a long string of text. But they placed the conversation title in a subdomain under cf.metaaiusercontent.com, alongside that string. According to Ars Technica’s account of Claroc’s findings, that design gave outsiders a way to search for the links rather than guess them.

The route was passive DNS: historical records of domain names being resolved to internet addresses. Monitoring systems collect those records by observing DNS responses at internet infrastructure. Commercial services make the resulting records searchable.

When an intended recipient opened a Muse share link, the domain lookup could enter that searchable history. The title could reveal a clue to its contents. Claroc called these discoverable pages GhostShares: conversations accessible to people who had never been handed the link.

A sample reached well beyond casual chats

The sensitive material came from a sample, not an inspection of all 6,800 links. Within it, Claroc found information it said was clearly not intended for public access, including:

• Executive-search preparation notes naming a frontier AI lab’s internal contact and the time of a confidential call.
• A marketing company’s revenue review marked for its CEO, and a small-business loan application including the requested amount.
• A bank fraud alert with a partial account number and a transaction’s amount and time.
• A real-estate investor’s performance report listing property addresses and exact return, income and mortgage figures.
• A full-year workplace vacation calendar listing dozens of employees and the weeks each would be away.

From unanswered outreach to a shutdown

Claroc co-founder and CTO Asaf Aprozper told Ars that the firm had contacted Meta without receiving a reply. After checking similar platforms, consulting colleagues and rereading Muse documentation, Claroc concluded the behavior was by design.

Meta had not immediately answered Ars’s emailed questions in its initial account. Futurism’s later coverage said Meta had told Ars it had switched sharing off.