Knowledge-Driven Large Language Models for Automating CVSS Score Prediction

In response to the continuous growth of software vulnerabilities, this paper introduces a hybrid artificial intelligence (AI) approach that combines large language models (LLMs) with structured cybersecurity knowledge graphs. Our method guides LLMs through explicit, expert-driven rules to predict Common Vulnerability Scoring System (CVSS) Base metrics directly from vulnerability descriptions. Experiments on five state-of-the-art models, including GPT-4o and DeepSeek, demonstrate significant gains. Our proposed knowledge-infused prompts lead to accuracy improvement in GPT-4o from 59% to over 82%, while the accuracy in the predictions of DeepSeek rose from 48% to 78%. Moreover, we show that this integration boosts cost-efficiency for lighter models. These results highlight the practical value of merging symbolic knowledge with LLM reasoning to achieve faster, more consistent, and interpretable vulnerability assessments.