Crushing masses of people, airborne viruses, and smelly air are not the only threats for travelers on Beijing's subway system as a hacker has revealed a new technology exploit that can bring havoc to the capital city's underground transportation maze.

Zhao Wu, a Chinese security expert and head of the Butian loophole response platform, revealed on his microblog that the Beijing subway official background management system has a vulnerability which can lead to hackers gaining control of subway lines.

This vulnerability was submitted by a white hat hacker to Butian loophole response platform, which was established by Qihoo 360. This platform encourages white hat hackers to discover manufacturer loopholes by providing cash and gift bounties and help manufacturers fix loopholes and eliminate potential risks as soon as possible.

According to information from Butian, hackers can take advantage of this Beijing transportation vulnerability to directly login to a system administrator account to add, delete or change information such as subway stations, surrounding attractions, and hotlines, so as to disturb the normal operation of subway.

At present, the related details of the vulnerability have been reported to Beijing subway and the National Computer Network Emergency Response Technical Team/Coordination Center of China. There has been no posted timeline on when this will be fixed.

The Beijing subway just implemented a fare increase and restructuring of how fares are calculated last week. It also opened new lines that extend the massive network to many more stations.