Meta Muse has exposed users' personal and business secrets through conversation share links, according to research from security firm Claroc reported Monday by Ars Technica. The researchers could enumerate 6,800 links that Muse users created for sharing conversations, then opened a few hundred of them and found information that was clearly not intended to be public. Meta told Ars it is suspending the sharing feature while it reviews the report and considers changes to how those links can be discovered.
Muse is Meta's new general-purpose AI agent, and it rose quickly to the top of Apple's App Store. To do its job, it autonomously fills out forms, books appointments, makes purchases, creates documents and carries out other actions, which requires access to most of a user's accounts. Meta has marketed the assistant as a platform built for privacy and security, so a leak of shared material lands directly on that promise.
How Claroc found the Muse GhostShares
Like many online services, Muse let users click an option to create a unique URL that anyone could use to load a page hosting a search, a conversation, an image or similar content. Such links usually contain a long sequence of text that cannot easily be guessed, and Muse seemed to follow that approach. But a central design decision in how the URLs were built made them easy to find.
The clearest problem was the conversation title sitting inside the web address rather than in the URL path. Simplified examples include home-sale-budget-9f21c8a3.cf.metaaiusercontent.com and loan-application-draft-a4c9e2.cf.metaaiusercontent.com. Once the intended person clicks a share link, the DNS information is recorded in searchable databases, so a passive DNS search through one of many commercial services can surface it. Asaf Aprozper, co-founder and CTO of Claroc, told Ars he reported the findings through Meta's bug bounty program on October 8 and also tried reaching people at Meta on LinkedIn, but got no reply either way.
- Muse share links used the domain name cf.metaaiusercontent.com.
