Meta Muse Exposes Users’ Personal, Business Secrets When They Share Conversations

October 20, 2026

Security researchers say Meta’s Muse AI assistant exposed thousands of users’ shared conversations because conversation titles were placed in subdomains that could be discovered through public DNS records. Meta has since suspended the sharing feature while it considers making changes. Ars Technica reports: Like many online services, Muse has allowed users to share searches, conversations, images, and similar content with other people. Such share features usually involve clicking an option to create a unique URL that anyone can use to load a page hosting the content. To keep potentially sensitive information from being accessible to unintended people, the URLs typically contain a long sequence of text that can’t be easily guessed.

Muse, which Meta CEO Mark Zuckerberg said last month was “built from the ground up for privacy and security,” seems to take the same precautions. But a central design decision for constructing URLs has made the links easy to discover. As a result, researchers from security firm Claroc said they were able to enumerate 6,800 links Muse users created for sharing conversations with others. After opening a few hundred of them, the researchers found information that was clearly not intended to be publicly available… […]. “If you had asked us beforehand, we would have guessed that gathering these would take real effort,” the researchers wrote. “It took one query.”

[…] The easiest way to discover the URLs is to perform a passive DNS search through one of many available commercial services. Passive DNS records store the historical resolution of domain names to IP addresses, as well as nameserver, and mail-server records over time. Passive DNS systems typically collect DNS responses from sensors positioned at recursive DNS resolvers or other infrastructure. A passive DNS record is generally created when a monitoring system observes a DNS response. In the case here, once the intended party clicks on the share link, the DNS information is recorded in a searchable database.

Claroc researchers were able to discover the Muse share links because all of them use the domain name cf.metaaiusercontent.com. Discovery is further made easy by the decision to add the conversation name to the URL, along with a long string of text. Simplified examples of such links are home-sale-budget-9f21c8a3.cf.metaaiusercontent.com, q3-revenue-review-7b1e42f0.cf.metaaiusercontent.com, and loan-application-draft-a4c9e2.cf.metaaiusercontent.com. It’s this last design decision, putting the conversation title in the subdomain rather than in the URL path, that makes public discovery possible.