Researchers say they used Anthropic’s Claude to turn an OpenAI forum bug into access to internal systems — a warning that everyday web tools can open the door to an AI giant’s back office.
Story Highlights
- Security team Hacktron reported using Claude Opus 5 to exploit OpenAI’s Discourse forum and reach internal assets.
- The exploit chain reportedly began with a heap overflow in HEIF image handling used by the forum’s processor.
- Reports say Claude Opus 4.8 stalled, but Opus 5 generated a reliable ARM64 exploit within hours.
- OpenAI was notified in July; public coverage landed in mid-September 2026, and a $6,500 bounty was reported.
What Hacktron Reported Doing and How They Did It
VentureBeat and Quartz report that Hacktron tested OpenAI’s community forum, which runs Discourse software, and targeted its image upload path. The team said Claude Opus 5 helped craft an exploit chain that started with a heap buffer overflow in HEIF image parsing used by the forum’s processing stack. That path reportedly led to code execution and pivoted to connected resources. Outlets say the team then reached an internal account and repository, consistent with a controlled security test.
Outlets describe a stepped approach to the exploit. Reports say the team first tried Claude Opus 4.8, but address space layout randomization blocked stable results. They then used Claude Opus 5, which produced a reliable ARM64 payload within hours, enabling a working chain against the image handler. Summaries vary on the final reach, with some saying a harmless pull request and others citing internal repository access, but all agree the entry point was the forum stack.
Timeline, Disclosure, and Reported Bounty
Quartz reports that Hacktron disclosed the issue to OpenAI in July, in line with coordinated vulnerability disclosure practices. Media coverage surfaced in mid-September 2026 across several outlets, which repeated the same core details about the Discourse forum, the HEIF image flaw, and the Claude-assisted exploit. Business Insider and others say OpenAI awarded a $6,500 bounty, signaling the company treated the event as a valid security finding rather than hostile activity.
Coverage does not include a detailed OpenAI statement describing scope or fixes, and the public record relies on outlet summaries of Hacktron’s account. Some summaries say researchers avoided changing sensitive code, while others emphasize that internal repositories and credentials were reachable. That difference affects how deep the breach went but does not change the shared account of the initial vector and the role of Claude Opus 5 in building a viable exploit.
Why This Matters for Everyday Users and Institutions
This story shows how a small bug in a public forum can become a bridge into a large company’s private systems. It also shows that advanced chatbots can speed up exploit development for skilled teams. Many readers on the left and right worry that powerful companies and government partners do not guard data well. This event taps that concern. If web forums and image tools are weak, then the systems that shape speech, jobs, and security are at risk, too.
KRYPTOCEAN AI RACE 🌊 • Sept 18, 2026
Three security researchers at Hacktron used Anthropic models Claude Opus 4.8 and Claude 5 to breach OpenAI staff accounts in under 72 hours. The operation penetrated OpenAI internal GitHub assets, including their Monorail repository.
This…
— KRYPTOCEAN.ETH (@KRYPTOCEAN_) September 18, 2026
Coordinated vulnerability disclosure exists to cut risk while fixes land. Academic work finds these programs help, but many reports still linger without fast action, even when policies exist. That gap fuels public anger that big players move slowly while regular people pay the price after breaches. The lesson is simple: patch the basics, keep public surfaces tight, and reward good reporting. When leaders ignore that, trust falls and everyone loses — not just the elites, but the rest of us.
Sources:
coinpedia.org, tradingview.com, blog.rankiteo.com, m.cnyes.com, ground.news
