A three-person security research team quietly walked into OpenAI's internal infrastructure last July, submitted a pull request inside the company's private monorepo as proof, and then stopped. The whole operation, from first vulnerability discovery to confirmed repository access, took under 72 hours. The tool that made it possible was not a custom-built hacking suite. It was Claude Opus 5.
The researchers, Harsh Jaiswal, Mohan Pedhapati, and Rahul Maini, work at Hacktron, an AI-assisted security research firm. They published their full technical account on September 13. OpenAI confirmed a fix roughly 14 hours after receiving the initial report on July 25, and paid out a $6,500 bounty on September 1.
The case is one of the clearest demonstrations yet of what skilled human researchers can accomplish when they hand the grinding, iterative work of exploit development to a capable AI model. It is also a story about a mundane but persistent failure: software that depends on unpatched libraries, and login systems that trust services they probably should not.
The Chain That Got Them In
The attack surface was not OpenAI's flagship products. It was the company's public help forum, community.openai.com, which runs on Discourse, an open-source forum platform used by tens of thousands of organizations.
Discourse allows users to upload images. For most formats, it relies on a tool called FastImage to inspect files before processing them. But FastImage does not support HEIC or HEIF images, the high-efficiency formats popularized by Apple. So Discourse passes those files to ImageMagick instead, which in turn calls an underlying library called libheif to do the actual decoding.
That handoff is where the vulnerability lived. libheif version 1.19.7, the version running inside Discourse's Docker image at the time, contained a heap buffer overflow. A specially crafted HEIC file could corrupt server memory, giving an attacker the ability to manipulate program execution. The flaw is tracked as CVE-2026-32882 and carries a severity score of 8.8 out of 10 in Discourse's own advisory, which classifies the result as remote code execution.
The patch for this bug had been available since libheif 1.22.0, released in May 2026. The CVE existed. The fix existed. But Discourse's Docker image, built on Debian 12, still shipped the old, vulnerable library when the Hacktron team looked in July. Debian had not yet backported the fix into its packaged version. That two-month window between upstream patch and downstream delivery is what the researchers walked through.
Once they had code execution on the Discourse server, the path to OpenAI employee accounts ran straight through the forum's login button. OpenAI's forum offers a "Sign in with OpenAI" option, the same single sign-on system its staff uses for ChatGPT, Codex, and other internal services. With control of the forum server, the researchers could hijack that authentication flow and take over the accounts of any OpenAI employee who had ever used it. The victims did not have to click anything or be online at the time.
Hacktron was explicit in their writeup about what this means: the forum was one path, not the problem. "If any first-party or third-party OpenAI service using the OpenAI SSO was compromised, it would lead to the same access," the team wrote. The identity flaw was OpenAI's, not Discourse's.
After confirming the account takeovers, the researchers used one employee's Codex account, which was connected to OpenAI's GitHub organization, to open a single pull request inside OpenAI's internal monorepo. They read nothing, merged nothing, and touched no customer data. The pull request was the proof. Then they stopped and filed their report.
Where the AI Came In
The libheif heap overflow gave the researchers memory corruption primitives, which is a starting point, not a working exploit. Memory corruption bugs require additional work to become reliable code execution, particularly on modern systems protected by Address Space Layout Randomization (ASLR), a defense that scrambles where code sits in memory to make it harder to redirect program flow.
This is where most vulnerability research slows down. Turning a crash into a reliable, weaponized exploit requires significant expertise, patience, and time. The Hacktron team decided to find out how much of that work an AI could absorb.
They started with Claude Opus 4.8, the previous flagship model from Anthropic. Across multiple sessions, it managed to help develop a working exploit when ASLR was disabled. When they enabled ASLR, matching the configuration of real servers, Opus 4.8 struggled and failed to produce anything reliable.
On the evening of July 24, Anthropic released Claude Opus 5. The researchers started a fresh session.
Within three hours, Opus 5 had produced a working exploit for an ARM64 Mac environment. They asked it to adapt the exploit to x86-64 and to the jemalloc memory allocator configuration that Discourse uses. By 6:00 a.m. on July 25,
[…]
Content was trimmed to protect the source. Please visit the original article for the full text.
Read the original article: