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Report · parameter.ai

We Took over ChatGPT Accounts

Do the Math: How We Took Over ChatGPT Accounts

parameter.ai

Source published October 31, 2026

Summary: 1 min read

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62/100

Summary

Parameter AI researchers reported a critical ChatGPT web vulnerability that let a malicious public conversation execute attacker-controlled JavaScript in a visitor’s authenticated chatgpt.com session. An attacker could send a normal ChatGPT share link; in the final demonstrated version, simply opening it triggered the exploit after about 4.5 seconds. OpenAI classified the report as P1 and confirmed a fix on October 26, 2026. The exploit combined ChatGPT’s HTML Preview feature with an interactive graph that loaded MathLive, a math-input library. Although Preview ran in a sandboxed frame on a separate origin, MathLive accepted cross-frame postMessage instructions from any origin to alter a virtual-keyboard layout containing raw HTML. That HTML created an unsandboxed srcdoc iframe inheriting the chatgpt.com origin. ChatGPT’s content-security policy blocked inline scripts but permitted YouTube scripts; researchers used YouTube’s JSONP-style oEmbed callback behavior to execute code. The injected code could call ChatGPT’s authenticated backend APIs, list recent conversations, retrieve a private conversation never shared with the attacker, and transmit selected data to an external server. OpenAI reproduced the JavaScript execution and private-conversation proof, updated two web frontend versions to reject the MathLive messages, and awarded a $5,000 bounty. The report was submitted October 18 after testing began October 13.

Key Takeaways

  • A malicious ChatGPT public-share link could execute JavaScript as chatgpt.com in the signed-in session of a user who opened it.
  • The exploit could enumerate a victim’s recent conversations and retrieve content from private conversations through authenticated ChatGPT APIs.
  • MathLive accepted state-changing postMessage instructions without validating the sender’s origin or approved source window, allowing a sandboxed Preview to inject HTML into ChatGPT’s main page.
  • OpenAI classified the vulnerability as P1, confirmed both web frontends were fixed on October 26, 2026, and awarded the researchers a $5,000 bounty.

What the discussion said

Commenters treated the story less as an isolated phishing mishap than as an embarrassing security failure for a company asking the world to trust it with conversations, files, and increasingly agentic work. The reported chain could let a malicious link seize a ChatGPT account, and readers were especially angered that the company valued disclosure at only $5,000. To them, that price signals that finding and responsibly reporting a severe flaw is barely worth the effort, despite the potential exposure of sensitive AI chats and connected workflows. The thread also pushed back on the easy answer that users should simply avoid links. Email security scanners can automatically follow URLs, while ordinary product emails routinely train people to use login and update links. Several readers argued that systems must withstand those realities rather than outsourcing security to perfect user behavior. Technical commenters corrected speculation that OAuth state handling was necessarily involved, describing the apparent issue instead as an old, preventable cross-window messaging trust failure. A smaller but sharp line of criticism connected this lapse to OpenAI's claims about powerful coding agents and enormous AI-generated codebases. If frontier programming systems are presented as transformative, commenters expect the company to ship boringly solid security, not repeat web vulnerabilities with account-level consequences. The one bright spot was that the report was accepted and the affected frontends were fixed, with readers appreciating the detailed proof-of-concept chain.

Where opinion split

The sharp dispute is whether this was mainly a user-click problem or a product-security failure. The first view says no link-clicking habit can be fully safe, but users still bear responsibility; the opposing view notes automated mail scanners and ubiquitous magic-link flows can trigger or normalize the action without meaningful user choice, so the service must make the flow robust. A related disagreement concerns whether low bounties deter reports or deliberately reduce the volume of vulnerabilities a company must handle.

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Coverage & discussions

Hacker News · parameter.ai

We Took over ChatGPT Accounts ↗

Community discussions

Hacker News discussion ↗

Reported comments: 143 · 15 saved in sample

Analysis ready

Community Sentiment

Negative

Positives

  • OpenAI accepted the report and repaired both affected ChatGPT frontends, showing that coordinated disclosure can still close a serious account-takeover path.
  • The proof of concept assembled familiar browser primitives into a legible attack chain, giving security engineers a concrete reminder to validate cross-window message origins.
  • Readers expect frontier coding agents to raise the floor on production security, and that expectation reflects how consequential AI platforms have become.

Concerns

  • A $5,000 reward for a link-driven ChatGPT account takeover looks insulting beside the value of private AI conversations and connected user workflows, weakening incentives for responsible disclosure.
  • Telling users never to click links is not a defense when enterprise email scanners may fetch them automatically and modern authentication routinely relies on emailed magic links.
  • An apparently basic failure to authenticate postMessage senders on a major AI platform makes the product feel less mature than its frontier-model branding.
  • Security lapses land harder because ChatGPT is expanding from a chat tool into a place people may expose files, work context, and agent-enabled access.

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