Security researchers found 35,578 Grok Build apps that opened without a sign-in, including one containing a confidential sales onboarding plan from Elon Musk's SpaceXSI.
SpaceXSI took down 24 apps built by its own staff and employees of X after security firm Claroc reported them, while other users' apps containing medical and employee data were still accessible when Claroc published its findings on 10 November 2026.
Claroc found the apps through records of internet address lookups, which let it discover links nobody had sent to its researchers.
The findings show that outsiders could open the apps, but whether anyone else used the links to steal data or tamper with records remains unverified.
What the Open Apps Contained
Of the 37,571 apps still online when Claroc tested them, 94.7% opened without a sign-in.
Most were games, landing pages or calculators, but the researchers found internal data linked to 30 identifiable organisations besides SpaceXSI and X, including six Fortune 500 companies, after using an AI model to flag pages for researchers to review by hand.
‼️BREAKING: Grok Build has left 35,000 of its users' apps open to anyone, including apps from SpaceXSI.The open apps held 3,784 medical exams of workers and a Tesla technician scorecard, plus a Navy contractor's roster and SpaceXSI's own sales plans.The "secret" words in each app's link sit in its web address, which DNS logs record, security firm Claroc found.Cursor, which SpaceXSI bought, says apps are private by default. Claroc's tests show otherwise.SpaceXSI pulled its 24 apps after Ars asked. Most other data was still exposed when Ars published.
— International Cyber Digest (@IntCyberDigest) November 10, 2026
The staff-built apps included a map of 594 enterprise sales accounts and advertising proposals from X. One proposal was marked confidential and prepared for a US federal agency.
Other examples included an occupational health dashboard covering 3,784 medical exams conducted on workers at a Peruvian construction company and a searchable roster of more than 3,500 hospital group employees. A separate app held an intensive care briefing for one patient.
How Grok Build's Share Links Were Found
Grok Build lets users describe an app in a chat and publish it at its own web address. When someone opens an app, their browser needs to look up its hostname, and those lookups can show up in searchable databases known as passive DNS records.
SpaceXSI said apps stay private until creators choose to publish them and that employee accounts default to 'Only you'.
In the paid account Claroc tested, 'Anyone with the link' was already selected when researchers reached the step where they could choose who could open the app once published.
Claroc switched one of its test apps to 'Only you' and found that an outside visitor could no longer open the page or reach the function that served its data.
The firm recommended making that setting the default at publication and adding an option to limit access to people with an email address at the same organisation.
What Claroc Tested and Who Was Notified
In a separate test, Claroc built an app for a fictional sales team and used an uninvited Google account to sign in, read customer records, edit one customer record and delete another.
The generated code added the visitor to the team before checking membership, and Claroc tested those actions only on apps it controlled.
Claroc reported the first two staff-built apps to SpaceXSI on 8 November and the other 22 the next day. All 24 links returned an error when checked at publication.
Claroc had emailed three other affected organisations by the time it published its findings. How many other apps have since been restricted and whether SpaceXSI has contacted their owners remain unclear.
