What is the ruling on a woman traveling to study at a university far from her city, given the widespread moral decay in universities and the fear of her being tempted in her religion and morals?

A Muslim woman is not permitted to travel except with her husband or a mahram (definition), based on the Prophet's (peace be upon him) saying: "It is not lawful for a woman who believes in Allah and the Last Day to travel for three (days) unless a mahram is with her." The prohibition becomes even stronger if the university is mixed-gender and widespread moral decay is prevalent within it; this type of university is not permissible for study. It is advisable to seek a safe university or pursue distance learning.