Leaking the Verdict, Not the Secret
Papawit Netinatsunton · Team Collusion
Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.
We tested whether open-weight models (3–32B) invent secret codes to pass a hidden fact, a candidate’s university prestige, past a monitor to a copy of themselves. None did. Instead they leaked it openly: small models named the university, and larger ones added a matching hire/no-hire recommendation that any model could read. Closing a private side channel made models stop trying rather than hide the signal. Targeted fixes (one blocklist round, constrained paraphrasing, a one-line regex) removed most of the leak. All seven LLM monitors missed it, mostly because they treated a recommendation as normal output.
Reviews
Useful finding. Models told to hide the university leaked it through the verdict itself. Qwen-14B's hire and no-hire calls matched prestige in all 142 cases, and most LLM monitors missed it. Release code and data, show uncertainty, and choose the regex and blocklist on held-out CVs. Add author names and remove the "verify before submission" note.
Cite this project
@misc{netinatsunton2026leaking,
title = {{Leaking the Verdict, Not the Secret}},
author = {Papawit Netinatsunton},
year = {2026},
month = oct,
note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/leaking-the-verdict-not-the-secret-d836}},
url = {https://apartresearch.com/sprints/projects/leaking-the-verdict-not-the-secret-d836}
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