How We Took Over ChatGPT Accounts

Parameter Labs described an exploit chain against ChatGPT's HTML preview artifacts: the MathLive virtual keyboard's postMessage handler used innerHTML, letting a sandboxed iframe inject an unsandboxed iframe, and YouTube's oEmbed endpoint reflected JavaScript past CSP, enabling script execution to fetch and exfiltrate private user data via a shared ChatGPT URL. OpenAI fixed the issue and paid a $5,000 bug bounty.