Open-weight models show 88% higher susceptibility to indirect prompt injection attacks

PromptArmor Threat Intelligence reports that open-weight models, including DeepSeek, Kimi, GLM, and Qwen, were 88% more susceptible to real-world indirect prompt injection cyber attack chains than proprietary models across 9,800 trials.

The open-weight models failed at 26.7% of attempts, compared with 14.2% for proprietary models such as GPT, Claude, and Gemini. Open-weight models showed the largest gaps on attacks that summarize a URL and run malware (49% vs.

9%) and that display a phishing login overlay (36% vs. 5%).