What is the ruling on one who was promoted in his job to a higher degree than he deserved, through nepotism and bribery?

If you are appointed to a lower position than you deserve, and this was an act of injustice and oppression, then it is permissible for you to pay a bribe to obtain your right, and the sin falls upon the receiver. However, it is not permissible to pay a bribe if the right can be obtained through other means, as Allah Almighty says: "But whoever is forced, without desiring it or exceeding due bounds, there is no sin upon him." As for the consequence of being appointed to a higher position than you deserve, you must inform the officials about it. If they approve your position, then praise be to Allah. If they do not, then you must return the excess money or spend it for the benefit of the Muslims. However, if the appointment was based on labor laws without injustice, then it is not permissible to achieve a higher position through bribery or mediation. If what you obtained was not your right, then you must repent to Allah, and it is permissible to remain in the job as long as you perform it as required.