Claude Opus 5 Helped Researchers Take Over OpenAI Staff Accounts via Chained Flaws

Summary

Three Hacktron researchers used Anthropic's Claude Opus 5 to chain a bug in Discourse, the open-source software behind OpenAI's public help forum, with a weakness in OpenAI's "Sign in with OpenAI" single sign-on, taking over ChatGPT and Codex accounts of several OpenAI employees and reaching an internal code repository. The team reported the flaws, proved access with a harmless pull request, and stopped; OpenAI confirmed a fix about 14 hours later and paid a $6,500 bounty on September 1.

Mitigation

Rebuild the self-hosted Discourse server on the latest image so it ships the patched libheif, since a web-interface update alone may not replace the old library. Fixed self-hosted releases are 2026.7.0, 2026.6.1, 2026.5.2, and 2026.1.6. Upstream libheif was fixed in 1.22.0 for CVE-2026-32882.

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