Researchers pose as hackers, exposing security flaw that could open your hotel-room door

There is a new warning for travelers after researchers, posed as hackers, expose a security flaw that could open millions of hotel-room doors.

The good news is, they're helping to fix the problem after Wired Magazine reported about the security vulnerabilities within the lock's encryption system.

"With just two taps, they can open these doors in seconds," said Andy Greenberg, a senior writer at Wired.

The researchers said using a key card, they cracked the code and essentially made a "master key."

"These security researchers have actually exposed this and that's a good thing because now dormakaba, the lock manufacturer, can start the process of trying to update all these locks around the world and fix this," Greenberg said.

They say the lock company has updated about one-third of the locks so far.

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"Our customers and partners all take security very seriously, and we are confident all reasonable steps will be taken to address this matter," dormakaba said in a statement.

"We also have to consider that they may have actually done it in the past these more professional, profit-motivated, or you know, politically-motivated hackers and they may have even exploited these locks in secret to get into hotel rooms for profit, or even for kind of intelligence purposes," Greenberg added.

How to protect yourself

How can hotel guests protect themselves? ABC News was told the locks in question have a round card reader with a wavy line cutting through it.

Apps can help you determine if it's been updated.

If it hasn't been, experts say the deadbolt won't help since it's connected to the keycard, so use your door's key chain instead.

The researchers have not revealed the exact method of how they made a master key, being careful as to not allow the information to get into the wrong hands.