Codex login page could leak your ID token anywhere

Codex's post-login setup page would send your ID token to whatever URL a platform_url value pointed at, per a pull request OpenAI merged September 10. That token can be replayed to impersonate you, no phishing page needed since the attacker only has to control the redirect target.

Nothing in the code required that URL to point back at OpenAI. The pull request that fixed it checks the redirect target against an exact match on two OpenAI platform hosts and rejects anything else.

OpenAI didn't publish a release note or a blog post for this one. The commit log is the only public record that the bug, or the fix, ever existed.

Anyone running Codex should update. The bigger check is for builders. An OAuth or SSO handoff with a configurable redirect target needs to match hosts exactly. Checking that a URL was present isn't enough.