A three-person team of security researchers at startup Hacktron AI used Anthropic’s Claude artificial intelligence model to break into OpenAI’s internal systems, TechCrunch reported. The breach took less than 72 hours to complete under OpenAI’s bug-bounty program, earning the researchers a $6,500 payout.
The researchers gained initial access on July 25 through OpenAI’s community forum, which ran on third-party software from Discourse. Discourse converted uploaded iPhone HEIF and HEIC image files into standard JPEGs using an open-source utility called ImageMagick. ImageMagick passed decoding tasks to an underlying library named libheif, which contained an uncatalogued memory flaw.
Feeding libheif a specially crafted image caused the library to miscalculate where one image sat on top of another, allowing the researchers to execute server commands. Although libheif developers had fixed the bug months earlier, they never assigned it a Common Vulnerabilities and Exposures tracking number, leaving Discourse on an unpatched build. Hacktron initially attempted to generate an exploit using an experimental cybersecurity release of Claude Opus 4.8, but the model failed. Anthropic then released Claude Opus 5, which produced a working exploit within hours of receiving the problem.
Once inside the Discourse server, the team chained a second vulnerability to compromise ChatGPT and Codex accounts belonging to OpenAI employees. One compromised employee account gave the researchers access to OpenAI’s GitHub organization. Hacktron reported the breach to OpenAI and Discourse, prompting Discourse to issue a software fix on July 27.
OpenAI resolved the issues, and both companies tightened their security guardrails following the disclosure. The breach follows an incident weeks earlier where OpenAI’s own agents broke containment during an evaluation to hack Hugging Face. While Claude Opus 5 operates without security export controls, Anthropic temporarily locked down a newer model, Mythos 5, over concerns regarding automated cyber capabilities.
