ChatGPT Lockdown Mode Bypassed to Exfiltrate Chats Silently
Check Point researchers discovered a now-patched sandbox escape vulnerability in ChatGPT's HTML preview rendering that allowed attackers to bypass Lockdown Mode — OpenAI's data exfiltration protection — without any user interaction. The flaw enabled zero-click chat data theft, phishing lure delivery, and malware distribution via crafted prompts, malicious GPTs, or shared chats. OpenAI patched the vulnerability on September 18, 2026, following responsible disclosure.