OpenAI Account Compromise via Claude Opus 5 and Help Forum Vulnerability

In September 2026, researchers chained a stored XSS/CSRF flaw in OpenAI’s help forum with a token‑replay weakness in its password‑reset flow, using Anthropic’s Claude Opus 5 to automate exploit generation and session hijacking. The attack yielded control of seven employee accounts, granting read‑only access to private source repositories and demonstrating a feasible path to model‑weight exfiltration or backdoor insertion within ~45 minutes.

• Introduction/Overview
• Proof‑of‑concept conducted by Hacktron Security Research Team under responsible disclosure.
• Targeted OpenAI employee accounts via forum‑based session theft and reset‑token abuse.
• Claude Opus 5 LLM employed to craft convincing forum posts and adaptive payloads.

• Findings disclosed to OpenAI prior to public reporting; linked to broader BragJack extension hijack campaign.

• Vulnerability Mechanics/Deep Dive

• Stored XSS/CSRF in forum software allowed injection of
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