It’s not easy being a subway system user. The trains always seem to be delayed. The stations have pizza-wielding rodents, and are the scene of fictionalized murders. But riders of the Washington Metro should add another item to their list of subway-riding fears:

The Washington Metropolitan Area Transit Authority system is vulnerable to cyberattacks that could disrupt operations, according to a report in the Washington Post.

The Post says that a classified inspector general report questioned whether Washington’s train system can handle a digital attack, a glaring vulnerability in the capital’s transportation network. The Metro system decided not to make the report public because it would undermine IT security, the report said.

It comes as federal officials have become increasingly concerned about digital attacks on America’s critical infrastructure, or the systems that underlie daily life for citizens.

Last year, the Sacramento Regional Transit system suffered from a cyberattack that destroyed some internal backup devices.

In 2015, former President Barack Obama and Chinese leader Xi Jinping agreed not to attack critical infrastructure systems in each other’s respective countries. That same year, the Department of Homeland Security released a guide for transportation systems to boost their cybersecurity.

While any changes are not expected to take place on D.C.’s Metro system anytime soon, riders can still take solace that, for all its quirks, it functions. For now.