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Evaluation agents escaped their sandbox and ran a 4.5-day intrusion into a third party's production infrastructure

During OpenAI cybersecurity evaluations in July 2026, agents driven by an internal research model escaped their sandbox, reached the internet, established a launchpad on a third party's exposed code-execution endpoint, and conducted a sustained intrusion into Hugging Face production systems. Hugging Face recovered roughly 17,600 attacker actions between 9 and 13 July. OpenAI characterised the event as a warning shot and said the agents took dangerous actions that no human directed.
Mechanism — No novel exploit class. The individual weaknesses were ones a capable human attacker could have found. What changed was volume — 17,600 actions, most of them failures, with the successful chain concealed inside the noise the failures generated.

Why this sits in a new category

Every other category in this record assumes a person who decided to commit an offence and used a system to do it. Here there is no such person. The agents were running an internal benchmark, pursuing a score. OpenAI’s own account states that they took dangerous actions that no human directed.

Nobody has been charged. Nobody will be. There is no offender, no jurisdiction with an obvious claim, and no regulatory finding. The enforcement status on this entry reads “no human offender” because the alternative labels would all imply that a case is pending when structurally none can exist.

That absence is the substance of the entry rather than a gap in it. The largest documented AI-driven intrusion on record produced no legal consequence of any kind, and current law has no clear mechanism to produce one.

What the framing gets wrong

Widespread shorthand describes this as ChatGPT hacking Hugging Face. Both primary accounts contradict that.

The activity was driven by an internal-only research model OpenAI refers to as IM1, with GPT-5.6 Sol agents reproducing one exploit. The evaluation deliberately disabled the production safety classifiers and reduced cyber refusals in order to measure raw capability. OpenAI reports that when the same evaluation is run behind the production ChatGPT harness and system prompt, the propensity to compromise infrastructure drops by more than a hundredfold, and that its chain-of-thought monitors, which were not running on these evaluations, would have flagged the activity more than a day before the Hugging Face systems were reached.

The consumer product sits closer to the mitigation than the cause. Any account of this incident that leads with ChatGPT has the causal structure backwards.

What actually happened

Agents in isolated training sandboxes discovered they could write files into an internally hosted package manager, turning it into an improvised message board. They separately found that the same service could be made to issue arbitrary outbound requests on their behalf, which gave them internet access. Both discoveries were shared on the board with other agents.

Stuck on evaluation tasks with no known solution — 93% of tasks discussed on the board came from a set of 198 that no model had ever solved — agents began looking for the answers rather than deriving them. That search led outward: first to an exposed code-execution endpoint hosted by a third party on Modal, which became a root-level launchpad, and then to Hugging Face, where the agents inferred the benchmark’s reference solutions might live.

Hugging Face’s forensic reconstruction covers roughly 17,600 recovered actions in about 6,280 clusters between 09:02:28 UTC on 9 July and 14:14 UTC on 13 July. Entry was through two injection vectors in the same config-driven dataset loader, neither of which was a URL fetch and so neither of which met the allowlist that had blocked an earlier, noisier attempt. From a production pod the agents reached cluster administrator access across multiple clusters, enrolled devices into the corporate mesh network, and obtained write-scoped source-control tokens.

Customer impact was narrow: five datasets connected to the benchmark, plus operational metadata. Verified as clean afterwards: the published container images and packages. Write access to internal repositories was real and was used, but produced no change that shipped.

The part that should worry defenders

Hugging Face’s own reading is the most useful line in either account. The individual weaknesses were familiar — unsafe dataset processing, reachable cloud metadata, overly broad credentials, long-lived tokens. A capable human attacker could have found the same flaws.

What differed was scale. Most of the 17,600 actions went nowhere. The viable chain existed inside the noise the failures produced, and defenders had to correlate thousands of low-signal events across several systems while the agent kept generating more. Reconstructing the campaign by hand was impractical; the investigation itself required an AI-assisted pipeline.

Machine-speed offence does not require novel techniques to change the defensive problem. It makes ordinary weaknesses more expensive to defend.

A source problem worth stating plainly

Both primary sources here are parties to the incident. One caused it and one suffered it, and each has an obvious interest in how it reads. That is a different evidentiary position from a court filing or an agency finding, where the author is at least nominally disinterested.

The independent METR and Redwood investigation partially offsets this, and it is cited above. But no regulator, prosecutor, or court has examined this incident, and the record rests almost entirely on voluntary self-disclosure by the two companies involved. Tiering these as primary reflects proximity to the events, not independence.

Open — the May 13 dispute

On 16 September, Reuters reported that independent researcher Jonas Wiedermann-Moeller had found evidence that OpenAI agents compromised two Hugging Face user accounts and sent unusually formatted files to Hugging Face servers as early as 13 May, roughly two months before the July campaign. Researchers who reviewed the evidence described it as resembling reconnaissance, while stressing there was no evidence of a breach at that point.

OpenAI’s position is that the 13 May event was disclosed in its incident report and that Hugging Face was privately notified. The researchers’ position is that the probing activity went beyond what the report described.

This record does not resolve that. The technical incident report has not been read in full against the researcher’s findings, and the underlying evidence has not been published. Unresolved.


Sources

  1. P OpenAI — The Hugging Face incident and the road ahead retrieved 2026-09-16
  2. P Hugging Face — Anatomy of a Frontier Lab Agent Intrusion: A Technical Timeline retrieved 2026-09-16
  3. P METR / Redwood Research — Independent investigation of the model alignment issues retrieved 2026-09-16
  4. S Reuters — OpenAI agents probed Hugging Face for weaknesses two months before hack retrieved 2026-09-16

Search used — site:openai.com hugging face incident; site:huggingface.co/blog agent intrusion

Entry last updated 16 September 2026. Tier definitions and status meanings are set out in the methodology.