Researchers used Claude to take over OpenAI staff accounts and reach internal code
A three-person security startup chained an image-upload bug to a login flaw, took over employee ChatGPT and Codex accounts, and opened a pull request inside OpenAI's private repository. The work was authorised, and OpenAI paid $6,500.
What happened
On September 18, OpenAI and the security startup Hacktron AI disclosed a break-in the company had already closed. The chain started on July 25 in the software that runs OpenAI's public help forum. Discourse, the forum platform, handed uploaded images to a conversion library called libheif, and a specially built image made that library miscalculate memory and give up control of the server. Discourse patched the flaw on July 27. From that forum server the researchers moved into a weakness in OpenAI's own single sign-on, which let them take over the ChatGPT and Codex accounts of OpenAI employees.
One of those employees had Codex connected to OpenAI's GitHub organisation, which put the researchers inside the company's private code. To show the reach without reading anything, they had Codex open a harmless pull request in the internal repository. The exploit itself was written by a model. The team first tried a version of Claude Opus 4.8 released for security researchers, which struggled across several sessions. Claude Opus 5 produced a working exploit within hours of its release. Less than 72 hours passed between the first finding and the internal repository. The vulnerabilities are fixed, and OpenAI paid the team a $6,500 bounty through its bug bounty program.
Before
Model-written exploits were a research claim. Getting from a public forum to a company's private code was work for a well-resourced team with time.
Now
Three people did it in under 72 hours, and the part they could not write by hand came from a model they rented. The path ran through ordinary things: an image upload, a login system, and one employee account that was connected to everything else.
Who it touches
- Any business whose staff connect work accounts to an AI tool, because the tool inherits whatever that account can reach
- Owners running a public forum, help desk or upload form on software somebody else patches
- Shops where one person's login touches the code, the billing and the customer list at the same time
- Security teams pricing bug bounties, now that three people and a model can find more than the price assumed
What it means for the business
The lesson is not about the labs. It is about connections. Every AI tool an owner switches on asks to be joined to something: the inbox, the drive, the CRM, the repository. Each connection inherits the permissions of the person who approved it, and almost nobody writes down which ones exist. When we build, every account is created under the owner's login and the owner's card, and the answer to what a tool can reach is a list somebody can read.
It also changes what a security question sounds like on a sales call. The useful question is no longer whether AI is safe. It is which of your accounts is connected to which tool, and who approved it.

On the Stacked Podcast · Sep 18
"we are really in the wild west of AI right now"
The hosts read the bounty as the real story: a path into a private repository was worth $6,500 to the company that owned it, and far more to anyone who did not report it. Their argument is that the bug bounty economy has to grow as fast as the models do, and that small operators should be asking friends to try breaking their own apps.
Watch at 6:44 ↗Fact check: The hosts said the exploit took about three hours. Reporting puts it at less than 72 hours from the first finding to the internal repository, with Opus 4.8 failing across several sessions before Opus 5 produced a working exploit within hours of its release.