In a demonstration for BBC News, cyber-security researchers were able to generate a map of users across London, revealing their precise locations.
This problem and the associated risks have been known about for years but some of the biggest apps have still not fixed the issue.
What is the problem?
Several also show how far away individual men are. And if that information is accurate, their precise location can be revealed using a process called trilateration.
Here’s an example. Imagine a man shows up on a dating app as “200m away”. You can draw a 200m (650ft) radius around your own location on a map and know he is somewhere on the edge of that circle.
If you then move down the road and the same man shows up as 350m away, and you move again and he is 100m away, you can then draw all of these circles on the map at the same time and where they intersect will reveal exactly where the man is.
Researchers from the cyber-security company Pen Test Partners created a tool that faked its location and did all the calculations automatically, in bulk.
They also found that Grindr, Recon and Romeo had not fully secured the application programming interface (API) powering their apps.