Several popular gay dating apps have been found to reveal their users’ precise location, according to a BBC report. Cybersecurity researchers, Pen Test Partners, were able to demonstrate to BBC News how a map could be generated using the leaked data, which pinpointed a users location.

Here’s how the BBC describes the method:

“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.”

The flaw in these apps that allows this has been known about for years, however, many companies have failed to take steps to remedy the situation – both Grindr and Romeo did not make changes.

The researchers wrote in a blog post: “We think it is absolutely unacceptable for app-makers to leak the precise location of their customers in this fashion. It leaves their users at risk from stalkers, exes, criminals and nation-states.”

LGBT rights charity Stonewall told BBC News: “Protecting individual data and privacy is hugely important, especially for LGBT people worldwide who face discrimination, even persecution, if they are open about their identity.”

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After discovering these vulnerabilities the researchers reached out to the app companies to make them aware of the situation and to tell them how to mitigate the risks. Recon told the BBC that it has since obscured exact user locations.

Grindr told BBC News that users had the option to “hide their distance information from their profiles”. It added Grindr did obfuscate location data “in countries where it is dangerous or illegal to be a member of the LGBTQ+ community”.

Scruff told BBC News it used a location-scrambling algorithm. It is enabled by default in “80 regions around the world where same-sex acts are criminalised” and all other members can switch it on in the settings menu.

Hornet told BBC News it snapped its users to a grid rather than presenting their exact location. It also lets members hide their distance in the settings menu.