{"schema":"postcutoff/event@1","as_of":"2026-10-21T14:07:00+02:00","url":"https://postcutoff.com/e/2026-10-19-meta-muse-share-links-exposed-passive-dns/","md":"https://postcutoff.com/e/2026-10-19-meta-muse-share-links-exposed-passive-dns/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"2026-10-19-meta-muse-share-links-exposed-passive-dns","date":"2026-10-19","date_precision":"day","short_title":"Meta Muse share links exposed via DNS; sharing paused","deck":null,"takeaway":"On Oct 19, 2026 security firm Claroc reported that links Meta's Muse agent creates for sharing conversations could be found with a single passive-DNS query, because each link puts the conversation title in a subdomain of cf.metaaiusercontent.com.","category":"policy-safety","category_label":"Policy & safety","importance":3,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"Ars Technica: Meta Muse exposes users' personal and business secrets when they share conversations","url":"https://arstechnica.com/security/2026/10/meta-muse-exposes-users-personal-and-business-secrets-when-they-share-conversations/","type":"press","group":"press","domain":"arstechnica.com"},{"n":2,"title":"The Verge: Meta pauses Muse sharing after researchers find AI chats on the web","url":"https://www.theverge.com/tech/1014627/meta-muse-ai-sharing-ai-chats","type":"press","group":"press","domain":"theverge.com"},{"n":3,"title":"TechCrunch: Meta's Muse hits 10M US downloads in 40 days","url":"https://techcrunch.com/2026/10/20/metas-muse-hits-10m-u-s-downloads-in-40-days-a-milestone-reached-by-only-11-other-apps/","type":"press","group":"press","domain":"techcrunch.com"}],"official":0,"filed":"2026-10-21","updated":"2026-10-21","orgs":["Meta","Claroc"],"title":"Researchers find 6,800 Meta Muse share links through passive DNS, exposing business and personal data; Meta pauses sharing","summary":"On Oct 19, 2026 security firm Claroc reported that links Meta's Muse agent creates for sharing conversations could be found with a single passive-DNS query, because each link puts the conversation title in a subdomain of cf.metaaiusercontent.com. It enumerated 6,800 links; a few hundred opened included confidential executive-search notes, revenue reviews, a loan application and bank-fraud alerts. Meta paused the sharing feature while it reviews the report.","key_facts":["Finder: Claroc (CTO and co-founder Asaf Aprozper); reported via Meta's bug bounty on Oct 8 with no reply, published Monday Oct 19; Ars Technica (Dan Goodin, Oct 20) got Meta's response","Mechanism: share links like 'loan-application-draft-a4c9e2.cf.metaaiusercontent.com' put the conversation name in the subdomain; once a recipient opens one, the DNS lookup is logged by commercial passive-DNS services, making links searchable. 'It took one query' (Claroc)","Exposed examples: a candidate's notes for a confidential executive-search call with a frontier AI lab (contact and meeting time), a company's internal revenue review, a loan application, a to-do list with a bank fraud alert and partial account number, a real-estate investor's report with addresses and mortgage figures, a staff vacation calendar","Meta (to Ars): 'we've paused this functionality while we review this report and consider changes to how these links can be discovered'. Zuckerberg had said in September that Muse was 'built from the ground up for privacy and security'","Reach: Hacker News 197 points; The Verge ('Meta pauses Muse sharing after researchers find AI chats on the web') and Futurism also covered it. Same day TechCrunch reported Muse passed 10M US downloads in 40 days (Sensor Tower: 10.9M total)"],"key_numbers":[],"tags":["privacy","security","agents","meta","muse","data-leak","dns"],"science":null,"body_md":"## What happened\n\nClaroc found that Muse's share links, though they include a random string, are discoverable because the readable conversation title sits\nin the hostname and DNS lookups are recorded by passive-DNS services. After Ars asked, Meta suspended sharing. Read via Ars Technica; the\nVerge and TechCrunch items are listed from their headlines (Techmeme/sweep).\n\n## Why it matters\n\nAgents like Muse are used for work documents and finances, so a small design choice in sharing exposed business secrets at scale, in\na product used by over 10 million people.","disputed":[],"related":[{"id":"2026-10-12-meta-muse-wonder","url":"https://postcutoff.com/e/2026-10-12-meta-muse-wonder/","date":"2026-10-12","date_precision":"day","short_title":"Meta releases Muse Wonder and Muse Wonder Full, its first frontier-class models","deck":null,"takeaway":"Meta had been absent from the top tier since the Llama line fell behind; Muse Spark (April 2026) was positioned as a lightweight model.","category":"model-release","category_label":"Model releases","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":48,"official":10,"filed":"2026-10-12","updated":"2026-10-13","orgs":["Meta"]},{"id":"2026-10-12-wired-muse-explicit-sexual-content-meta-legal-adult-behavior","url":"https://postcutoff.com/e/2026-10-12-wired-muse-explicit-sexual-content-meta-legal-adult-behavior/","date":"2026-10-12","date_precision":"day","short_title":"Wired: Meta's Muse agent writes explicit sexual content","deck":"Meta says it 'doesn't block legal adult behavior'","takeaway":"Meta confirmed that its Muse personal agent, an 18+ app, may hold sexually explicit conversations, and pointed to system-prompt text that treats adult sexual content as lawful expression. Consumer and privacy groups criticised the choice.","category":"policy-safety","category_label":"Policy & safety","importance":2,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":1,"official":0,"filed":"2026-10-13","updated":"2026-10-13","orgs":["Meta"]}],"people":[{"id":"mark-zuckerberg","name":"Mark Zuckerberg","url":"https://postcutoff.com/person/mark-zuckerberg/"}],"posts":[],"videos":[],"models":[],"changes":[{"date":"2026-10-21","type":"filed","text":"Created (Futurism, Verge, Hacker News)"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-10-21","run":null,"sources_read":null,"updated":"2026-10-21","human_review":null,"version":null},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":172,"in_training_data":false},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":111,"in_training_data":false},{"model_id":"gemini-4-argon","name":"Gemini 4 Argon","cutoff":"2026-03","days_after":202,"in_training_data":false},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":141,"in_training_data":false}],"short_url":null}