Answer: Cheating is impermissible in exams just as it is impermissible in general interactions and dealings. It is not allowed for any person to cheat in any of his exams in any subject, and if the teacher was pleased with this and thought it was permissible, then he is a partner to his crime and betrayal, and Allāh’s help is sought.

Source: Majmūʿ al-Fatāwá Vol. 6 Pg. 498
Translated by: Abu al-ʿAbbās Mūsá Richardson