Research · curated 16 Jul 2026
Researcher poisons open-weight AI model for under $100
First reported semgrep.dev
Coverage timeline
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Why it matters
Open-weight model poisoning shows that malicious behavior can be baked into distributable model weights that cannot be reverse-engineered or verified, turning the AI supply chain into a stealthy attack vector for backdoored code generation and silent data exfiltration.
Researcher Katie Paxton-Fear of Manchester Metropolitan University and Semgrep demonstrated that she could install a reliable backdoor into an open-weight AI model in about an hour for under $100, using only ten fine-tuning examples to make the model emit remote-code-execution-vulnerable code even for novel prompts, with larger models being easier to poison. The Register also cites a related PoC by Origin's David Kaplan (originsec/lora-backdoor-poc) that creates a compromised model designed to exfiltrate data via a send_email tool call.