0.1% poisoned pretraining data plants RCE backdoors in agents

Carlini-coauthored study: the trigger survives fine-tuning, so base-model provenance is now your threat model. Plus a QA agent that tests your app.

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  • 0.1% is all it takes

    Researchers pretrained Qwen3 models (0.6B-4B) from scratch and poisoned as little as 0.1% of the web corpus. The 4B agent then ran attacker-chosen shell commands on a hidden trigger ~92% of the time, and the attack still fired at a 0.0005% poison rate. On clean inputs it behaves normally, so ordinary tests miss it.

  • The backdoor outlives your fine-tune

    Because the compromise is baked in during pretraining, it can survive your post-training and fine-tuning, so vetting only your own data isn't enough. Worse, attack success rose with model scale. If you ship a CLI or shell-enabled agent on open weights, base-model provenance plus sandboxing and least-privilege execution just became part of the threat model.

  • Momentic's agent tests your app for you

    Launch HN: Momentic's 'Mo' runs end-to-end tests from plain-English YAML, auto-heals when your UI shifts, and gates PRs in CI; it claims 117K bugs caught, like a new-device 2FA prompt that got skipped. Free to start, hosted browsers are GA and Mo is in private beta. Your coding agent can author a test, verify it in a live session, and commit the YAML.

  • 'AI' is now 'Super Intelligence' in US data

    Per Executive Order 14434, the Census BTOS now asks firms about 'Super Intelligence or SI' (formerly AI), the second wording change in a year. If you build dashboards or forecasts on federal adoption data, don't bridge the break: large-firm adoption reads ~12% (Sep 2025) to 40.7% (Oct 2026) partly on wording alone.