Around 18,700 University of Virginia (UVa) student social security numbers have been exposed by mistake due to a mailing error.

Aetna Student Health, the university's insurance provider, mailed open-enrolment brochures to students' homes through a third party vendor, informing them about health insurance options for the 2013-14 academic year. The students' confidential numbers appeared on the outside of the envelopes. The numbers were printed above their names on the address labels.

Andrew Elliott, a student who received the brochure, said that the numbers did not resemble the pattern of a social security number.

"It's definitely easily visible if you know what you're looking for," said Elliott. "It isn't separated by the little dashes, but it still looks like a Social Security number."

Cynthia Michener, Aetna spokesperson, apologised for the error. The organisation is now working with the university to ensure that this unfortunate situation does not occur again.

The university officials learnt about the mailing mishap last week.

"The university certainly regrets that this exposure occurred. Our focus is on notifying those affected, providing them information regarding credit monitoring and assistance, and ensuring that such an incident will not occur again," said McGregor McCance, the University spokesperson.

Officials are unaware whether Aetna or the university checked the mails before they were sent.

Some UVa students were shocked and disturbed to hear about the incident and expressed their discontent against the mailer.

Referring to the mailer, Hilde Franklin, a fourth-year student said, "Dude, you only have one job."

"As young students, many of us haven't really built our credit yet and as we start to build our credit this could actually hurt us," said UVA student Akwasi Asante.

Responding to the university's credit-monitoring assistance, Sharon Holman, a UVA student said, "I think that's a step that can help but there's very little they can do to take this back. It's something that is going to take years for us to fix those types of mistakes."