The complexity of implementations and the interconnection of assorted systems and devices facilitates the emergence of vulnerabilities. Detection systems are developed to fight against this security issue, being the use of Artificial Intelligence (AI) a common practice. However, the use of AI is not without its problems, specially those affecting the training phase. This paper tackles this issue following a two-fold approach. First, an AI-based vulnerability detection system based on code and token metrics, dubbed VulCoT, is developed. It reaches state-of-the-art performance while being suitable for C#, C/C++ and PHP. Second, the impact of poisoning attacks on VulCoT is analysed. Results show that VulCoT is specially affected beyond 20% of false data. Remarkably, detecting some of the most frequent Common Weakness Enumeration is altered even with lower poison rates. Overall, KNN and SVM are more appropriate for system protection in C# and C/C++, while MLP in PHP. Indeed, PHP is the language which is less affected by attacks, while C# and C/C++ present comparable results.