Grok Build app links exposed private data from thousands of users

Grok Build, the vibe-coding agent from SpaceXSI, has exposed confidential data belonging to thousands of its users. The company was formed when SpaceX and xAI merged, and its own internal files were among the material exposed. Security firm Claroc reported the problem, which it traces to how the platform builds and shares app links.

Grok Build lets people describe an app in plain language and publish it within minutes. Each app gets its own web address under grok.me. Claroc says the design was meant to make those addresses hard to guess, but a flaw undid that protection.

The start of each address uses random words, which Claroc calls dice words. Sources give different word counts. Ars Technica says two or more words, while Engadget and TechRadar describe four-word phrases. Claroc says a phrase of three such words carries about 38 bits of entropy, which gives billions of combinations.

The random part sits on the wrong side of the domain name, where passive DNS services can record it. These services log lookups made by DNS servers. A new address can therefore appear in a searchable database even when no one has shared it. Using this method, Claroc found 43,601 addresses ending in grok.me.

According to Ars Technica, more than 35,000 of those addresses, close to 95 percent, opened without a password. TechRadar gives a slightly different figure of 35,578, or 94.7 percent. Claroc also found that the default sharing option on Grok Build was the most open setting. The other two options are invited users and only you. Ars Technica reports that the company's own tests showed users had to change the setting by hand to make an app private.

The exposed material included internal business plans, advertising proposals and sales territory data. Claroc found 24 apps built by SpaceXSI itself. These held an onboarding plan for a new enterprise sales staff member, a sales territory map of 594 accounts, and internal system addresses for sales tools. Other exposed records reportedly belonged to a Peruvian construction firm with 3,784 worker medical exams and to a US Navy logistics contractor with a roster of 108 people. Some files listed employee names and identification numbers. A luxury cruise line galley checklist also appeared. Engadget reports that the leak touched a hospital group and a fire department. TechRadar says about one in ten apps held sensitive or internal business information. Claroc put the share of apps with the most serious material at 2 percent.

Claroc notified SpaceXSI on a Sunday. When there was no reply, the researchers tagged Elon Musk and Grok Manager Matt Palmer on X. Ars Technica reports that SpaceXSI then removed the links to its 24 own apps, which began to return an app-not-found error. Claroc says the other exposed apps were still open at the time of its statement. TechRadar reports that SpaceXSI remediated the issue after disclosure, so the sources differ on how far the fix went. Some affected organisations acted quickly, and the luxury cruise company reportedly brought in its full security team.

Cursor, which SpaceXSI recently acquired, told Ars Technica that Grok Build apps are private by default. Claroc's tests contradict that statement. Cursor also said that rival coding agents from ChatGPT, Lovable and Bolt offer shareable links too, and Ars Technica says that part of the statement is accurate. Muse, a Meta agent, recently suspended a link-sharing feature after a similar leak.

It is not yet clear how many of the exposed apps still hold live data. It is also unknown whether every affected company has finished its own clean-up. Claroc says it is still contacting organisations whose data was found.