Insecure Storage of Sensitive Information

Summary

A Storage of Sensitive Data in a Mechanism without Access Control vulnerability was identified in scikit-learn package verisons prior to 1.5.0rc1, in "TfidfVectorizer". The vulnerability arises from the unexpected storage of all tokens present in the training data within the `stop_words_` attribute, rather than only storing the subset of tokens required for the "TF-IDF" technique to function. This behavior leads to the potential leakage of sensitive information, as the `stop_words_` attribute could contain tokens that were meant to be discarded and not stored, such as passwords or keys. The impact of this vulnerability varies based on the nature of the data being processed by the vectorizer.