Her unstable magic causes her clothes to disintegrate.

Cinder managed to obtain half of the Fall Maiden's power and ventured to Beacon to finish what she started; however, she would soon learn that having two Fall Maiden's existing at the same time can have disastrous effects.

Walking through the hallway Cinder contemplates her mission's impending success.

Cinder: (Now that I'm in Beacon I can begin the next phase of my operation and claim what is rightfully mi-!?)

Just then the magic in her body starts to go erratic and felt intense pain and heat flow throughout her being.

Cinder: (What's happening? Why do I feel like my whole body could burst into flames at any second?) she thought.

Well to give credit where credit is due, she was half right but instead of her body, it was her clothes that burst into flames before completely turning to dust and leaving the now half Maiden naked as the day she was born.

Cinder: MY CLOTHES!!!

She begins to try to see if she can use her powers to possibly cover herself but now her magic isn't responding.

Just then the fire alarm goes off no doubt caused by the heat from the sudden flames that so quickly disappeared as it appeared.

Now on top of her powers short-circuiting, she is completely naked in the hallway of Beacon with no scroll to contact her team and the possibility that at any moment she could be seen by the other students.