“Grindr is a relatively unique place for openness about HIV status,” James Krellenstein, a member of AIDS advocacy group ACT UP New York, told BuzzFeed News.

But the new analysis, confirmed by cybersecurity experts who analyzed SINTEF’s data and independently verified by BuzzFeed News, calls into question how seriously the company takes its users’ privacy.

Grindr was founded in 2009 and has been increasingly branding itself as the go-to app for healthy hookups and gay cultural content. In December, the company launched an online magazine dedicated to cultural issues in the queer community. The app offers free ads for HIV-testing sites, and last week, it debuted an optional feature that would remind users to get tested for HIV every three to six months.

“The HIV status is linked to all the other information. That’s the main issue,” Pultier told BuzzFeed News. “I think this is the incompetence of some developers that just send everything, including HIV status.”

Because the HIV information is sent together with users’ GPS data, phone ID, and email, it could identify specific users and their HIV status, according to Antoine Pultier, a researcher at the Norwegian nonprofit SINTEF . (SINTEF was commissioned to produce the report by Swedish public broadcaster SVT , which first publicized the findings.)

The two companies — Apptimize and Localytics, which help optimize apps — receive some of the information that Grindr users choose to include in their profiles, including their HIV status and “last tested date.”

The gay hookup app Grindr, which has more than 3.6 million daily active users across the world, has been providing its users’ HIV status to two other companies, BuzzFeed News has learned.

“To then have that data shared with third parties that you weren’t explicitly notified about, and having that possibly threaten your health or safety — that is an extremely, extremely egregious breach of basic standards that we wouldn’t expect from a company that likes to brand itself as a supporter of the queer community.”

SINTEF’s analysis also showed that Grindr was sharing its users’ precise GPS position, “tribe” (meaning what gay subculture they identify with), sexuality, relationship status, ethnicity, and phone ID to other third-party advertising companies. And this information, unlike the HIV data, was sometimes shared via “plain text,” which can be easily hacked.

“It allows anybody who is running the network or who can monitor the network — such as a hacker or a criminal with a little bit of tech knowledge, or your ISP or your government — to see what your location is,” Cooper Quintin, senior staff technologist and security researcher at the Electronic Frontier Foundation, told BuzzFeed News.

“When you combine this with an app like Grindr that is primarily aimed at people who may be at risk — especially depending on the country they live in or depending on how homophobic the local populace is — this is an especially bad practice that can put their user safety at risk,” Quintin added.

Grindr said that the services they get from Apptimize and Localytics help make the app better.

“Thousands of companies use these highly-regarded platforms. These are standard practices in the mobile app ecosystem,” Grindr Chief Technology Officer Scott Chen told BuzzFeed News in a statement. “No Grindr user information is sold to third parties. We pay these software vendors to utilize their services.”

Apptimize and Localytics did not respond to requests for comment. Chen said that these companies will not share users’ data: “The limited information shared with these platforms is done under strict contractual terms that provide for the highest level of confidentiality, data security, and user privacy.”

Even so, security experts say, any arrangement with third parties makes sensitive information more vulnerable.

“Even if Grindr has a good contract with the third parties saying they can’t do anything with that info, that’s still another place that that highly sensitive health information is located,” Quintin said. “If somebody with malicious intent wanted to get that information, now instead of there being one place for that — which is Grindr — there are three places for that information to potentially become public.”

Under the app’s “HIV status” category, users can choose from a variety of statuses, which include whether the user is positive, positive and on HIV treatment, negative, or negative and on PrEP, the once-daily pill shown to effectively prevent contracting HIV. (The app also links to a sexual health FAQ about HIV and how to get PrEP.)

But just because users are comfortable sharing personal information in their profile or chats doesn’t mean they want it being shared more broadly.

“Some people’s jobs may be in jeopardy if the wrong people find out about their status — or maybe they have difficult family situations,” said Chris Taylor of Seattle, who uses Grindr but no longer displays his HIV positive status on his profile. It’s “disconcerting,” he said, that Grindr is sharing this information with other companies. “It can put people in danger, and it feels like an invasion of privacy.”

The disclosure of HIV status also raises questions about the app’s privacy policy, which states: “You may also have the option to provide information concerning health characteristics, such as your HIV status or Last Tested Date. Remember that if you choose to include information in your profile, and make your profile public, that information will also become public.”

But the average person may not know or understand what they’ve agreed to in the fine print. Some experts argue that Grindr should be more specific in its user agreements about how it’s using their data.

“What the law regards as informed consent is in almost all instances uninformed consent,” Ben Wizner, director of the ACLU Speech, Privacy, and Technology Project, told BuzzFeed News.

“I hope that one small silver lining here will be that users and citizens will realize that there are enormous loopholes in the privacy regime,” he said, “and that personal information is bought and sold freely on a global market.”