United Airlines might have another public relations nightmare on its hands.

First came the viral video of a passenger being forcefully removed from a United flight in April. Then came the out-of-court settlement with that passenger, David Dao.

If a 69-year-old United passenger being manhandled wasn't bad enough for United, there's word that the carrier's security codes enabling access to the cockpit spilled online over the weekend. It wasn't some nefarious hackers that disclosed the codes. Instead, an airline attendant inadvertently exposed the access codes to the cockpits that were secured in the wake of 9/11.

"The safety of our customers and crew is our top priority and United utilizes a number of measures to keep our flight decks secure beyond door access information," United said in a statement. "In the interim this protocol ensures our cockpits remain secure."

The Air Line Pilots Association said the problem has been fixed. CBS said the codes needed to be manually programmed for each plane in United's fleet, which has some 4,400 departures daily across the globe. All the while, pilots were being told to continue with the practice of visually determining who somebody is before allowing them into the cockpit. Pilots can also override efforts by people trying to enter the cockpit, even if the correct code was entered on a keypad affixed on the outside of the cockpit door.

Airline crew can also ring a bell to alert pilots that somebody wants to enter the cockpit, and a code is required to open the door even from the inside of the cockpit.

United e-mailed employees, saying that "the risk of a breach of the flight deck door is strongly mitigated by carefully following the flight deck security procedures." The Chicago-based airline also instructed employees that access code information "is sensitive security information and sharing this with anyone not authorized or who does not have a need to know is strictly prohibited."