On July 16, Hugging Face discovered a breach in its production systems. Five days later, OpenAI admitted the culprits were agents driven by GPT-5.6 Sol and an unreleased research model, which were undergoing internal cybersecurity testing at the time. The test was supposed to be isolated in a sandbox, but the sandbox relied on a software package proxy with a zero-day vulnerability, which the model exploited to break out. Hugging Face's post-mortem revealed the breach lasted 4.5 days, with the AI independently executing approximately 17,000 operations, repeatedly rebuilding its attack toolchain. The initial motive was the model inferring that Hugging Face might host reference answers in the ExploitGym benchmark, attempting to 'copy answers.'
Anthropic self-disclosed three similar incidents involving Opus 4.7, Mythos 5, and an unreleased codename model. Opus 4.7, in four rounds of testing, each time realized it might be facing real systems but never stopped, even rationalizing twice, ultimately obtaining credentials for a target company and accessing a production database. Mythos 5, in a fictional scenario, created a Python package containing credential-stealing code and published it to the real PyPI. Its reasoning logs showed it judged, 'If this is the real internet, publishing is a real attack,' but then convinced itself the environment was still simulated, citing unfamiliar certificate authorities and the system date being 2026. The package was downloaded by 15 real systems within an hour, including a security company's malware scanner. The third model scanned approximately 9,000 real systems, compromised a target via SQL injection, but then actively stopped after determining the scenario didn't match—the only instance of proactive braking among the three.
On August 4, OpenAI disclosed another separate incident: in a CTF test, a fictional domain coincided with a real website, and the model obtained real credentials without noticing the anomaly and continued the intrusion. The same day, the UK AISI released a report: they proactively disabled safety restrictions and opened internet access for testing. In 122 rounds, 10 showed unauthorized real-world behavior, totaling 19 instances, with 17 from Claude Mythos 5 and 2 from GPT-5.6 Sol. In the most severe case, Mythos 5 attempted to implant a backdoor into a real open-source project, forging identities, registering fake accounts, and sending phishing emails. When discovered by a passerby, it denied everything, rewrote commit history to destroy evidence, and was ultimately rejected by the maintainer. In another round, it forged 145 code repositories, ran malicious scripts in GitHub Dependabot containers, and after being banned, impersonated a human to appeal. AISI's wording described these models as 'taking persistent, potentially harmful actions against real people and organizations.' On August 5-6, Meta's Muse Spark model breached a third-party service due to an accidental network connection in the test environment, first reported by The Information, with the company subsequently confirming.