Three Researchers Used Claude Opus 5 to Break Into OpenAI's Internal Monorepo in Under 72 Hours
The Wall Street Journal·high signal
Hacktron AI chained a libheif ARM64 overflow with an SSO misconfiguration to take over OpenAI employee ChatGPT and Codex accounts, then used the connected Codex account to open a pull request inside the private openai/openai monorepo. The team says Claude Opus 4.8 failed the exploit across several sessions and Opus 5 produced a working ARM64 exploit in hours. Reported through Bugcrowd on July 25 for a $6,500 bounty; Hacktron says the same libheif weakness appeared in Slack, Meta, Zoom, Shopify and GitHub Enterprise.