NEWS · COMPANIES · #2249
Researchers say Meta's Muse share links expose users' sensitive conversation content
Security firm Claroc reported that Muse share links use the domain cf.metaaiusercontent.com and include the conversation title in the subdomain, allowing researchers to enumerate about 6,800 shared links via passive DNS and access dozens of conversations containing sensitive personal and business information. Claroc called the phenomenon "GhostShares," said the behavior appears to be by design, and reported contacting Meta without a reply; the disclosure follows other Muse security concerns including a recent macOS zero-day reported by researcher Patrick Wardle.
KEY POINTS
- Security firm Claroc reported that Muse share links use the domain cf.metaaiusercontent.com and include the conversation title in the subdomain, allowing researchers to enumerate about 6,800 shared links via passive DNS and access dozens of conversations containing sensitive personal and business information.
- Claroc called the phenomenon "GhostShares," said the behavior appears to be by design, and reported contacting Meta without a reply; the disclosure follows other Muse security concerns including a recent macOS zero-day reported by researcher Patrick Wardle.
- The design choice to include conversation titles in Muse share URLs (on cf.metaaiusercontent.com) makes supposedly private shares discoverable via passive DNS, raising material privacy and security concerns about the product.
DECISION BRIEF
CONFIDENCE
WHAT CHANGED
Security researchers from Claroc reported they could enumerate roughly 6,800 Muse “share” links and, after opening a few hundred, accessed dozens of conversations that contained sensitive personal and business information. Meta has paused Muse’s sharing functionality while it reviews the report and considers changes.
WHY NOW
Researchers demonstrated a low-effort, reproducible method (using passive DNS data) to discover many Muse share URLs and directly showed sensitive content in those shares; Meta responded by pausing the sharing feature, making this an active product-change and privacy issue now.
WHO IS AFFECTED
Directly affected are Muse users who created share links and any persons or organizations named or represented in the shared conversations that researchers opened. Indirectly affected are users relying on Muse’s sharing feature for private or sensitive content.
CONFIRMED
• Claroc researchers enumerated approximately 6,800 Muse share links. • After opening a few hundred of those links, researchers found conversations containing sensitive personal and business information (examples in reporting include candidate notes for a confidential hiring call; an internal company revenue review; a small-business loan application; a to‑do list with a bank fraud alert and partial account number; a real-estate investor’s performance report with addresses and financial figures; and a workplace vacation calendar). • Researchers used passive DNS searches as the straightforward method to discover the URLs (passive DNS records captured the DNS resolution when an intended party clicked the share link). • Meta said it has paused the Muse sharing functionality while it reviews the report and considers changes. • Meta stated it opened a Muse bug bounty program for researchers to report issues.
UNCERTAIN
Missing or unresolved in the supplied excerpts: • The excerpts do not state the exact domain or URL structure (for example, whether conversation titles appear in a subdomain) used for Muse share links — reporting elsewhere has named cf.metaaiusercontent.com but that domain string is not present in these excerpts. • Whether the observed behavior (URL discoverability) was an intentional design decision or an unintentional flaw is not established in the provided excerpts. • The full scope of exposed content beyond the sampled few hundred links (including whether others accessed these links before researchers) is not documented in the excerpts. • Whether Meta will implement specific technical or policy changes, and what those changes would be, is not described in the excerpts. • Any evidence of abuse or malicious exploitation of the discovered links is not included in the supplied excerpts.
WHAT TO WATCH
Observable signals to monitor next (concrete): • Public statements or product-notes from Meta about Muse sharing (re-enabling, redesign, or permanent removal). • Bug-bounty or security disclosures from Meta or Claroc with technical details about link structure and discovery method. • Claroc follow-up reports or technical writeups showing exact discovery steps, URL formats, or counts beyond the initial ~6,800. • Passive DNS dataset changes showing drops or removals of the relevant records or new domains used for Muse shares. • Evidence in news or security forums of third-party access, exploitation, or abuse of enumerated Muse share links. • Updates to Muse privacy/security documentation or terms describing sharing behavior and protections.
WHY IT MATTERS
The design choice to include conversation titles in Muse share URLs (on cf.metaaiusercontent.com) makes supposedly private shares discoverable via passive DNS, raising material privacy and security concerns about the product.
EVIDENCE MAP
4Editorial claims linked to specific sources, with support, contradiction and context shown separately.
Muse provides a sharing feature that creates unique web URLs to share searches, conversations, images, and similar content.
SUPPORTEDChecked 2026-10-21 · 2 supporting
Researchers said they were able to enumerate about 6,800 Muse share links.
SUPPORTEDChecked 2026-10-21 · 2 supporting
After opening a few hundred of those links, researchers found clearly unintended sensitive information, including candidate notes for an executive-search call; a national marketing company's internal revenue review; a small-business owner's loan application; a to‑do list containing a bank fraud alert with a partial account number; a real-estate investor's internal performance report with addresses and exact financial figures; and a workplace's full-year staff vacation calendar.
SUPPORTEDChecked 2026-10-21 · 2 supporting
According to Ars, the easiest way to discover the URLs was to perform a passive DNS search; passive DNS stores historical DNS resolution data.
SUPPORTEDChecked 2026-10-21 · 1 supporting
Ars explains passive DNS as the easiest way to discover the URLs and describes what passive DNS records contain.
CONTEXT WIRED AIMEDIA · 2026-10-21Wired reports the researchers enumerated many links but the provided excerpt does not include the passive DNS explanation.
SOURCES & TIMELINE
2Muse, the new general-purpose AI agent from Meta, can expose sensitive information when users share conversations through web links, researchers reported Monday. In response to questions from Ars about the behavior, Meta said it’s suspending the sharing feature while the company reviews it and considers making changes. Like many online services, Muse has allowed users to share searches, conversations, images, and si…
Muse, the new general-purpose AI agent from Meta, can expose sensitive information when users share conversations through Web links, researchers reported Monday. Like many online services, Muse allows 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 conten…