A prayer app launched by Pope Francis in 2019 contained a security flaw that exposed the personal information of hundreds of thousands of users before it was finally fixed this year.
The app, Click To Pray, was developed by La Machi Communication for Good Causes for the Pope’s Worldwide Prayer Network. Pope Francis endorsed the service and had an account on it. The app offers a “digital community of prayer” by guiding people through three prayers each day.
In January this year, independent researcher BobDaHacker discovered a flaw in the app’s API endpoint. An API is an online service that responds to requests for data. Typically, only the mobile app should send such requests, and the API should only return information about the specific person using that app. However, BobDaHacker found it was giving out information about any of the app’s users to anyone who asked.
Apps typically query an endpoint by sending it a specific ID for the person using it. In this case, those IDs were simply sequential numbers. According to BobDaHacker, there were 719,517 registered IDs for the app, meaning over 700,000 users had information stored in the system.
The problem was that the API didn’t check whether someone requesting a record was actually authorised to see it. Anyone could request information for any ID, from 1 through to 719,517. The API would then return that user’s record, including:
- Email address
- First and last names
- Country
- Date of birth
This kind of flaw is known as an Insecure Direct Object Reference (IDOR) and we’ve seen it before. Stalkerware-type app TheTruthSpy was found leaking details on its victims via an IDOR vulnerability in 2022, and it still hadn’t been fixed two years later. The web server for the MiCODUS MV720 vehicle-tracking GPS device also had the vulnerability in 2022, putting 1.5 million people at risk.
A second flaw in the Click To Pray API made things worse. When people register with an app, the service typically sends a link to their email address containing a unique code known as a validation hash. Clicking the link proves they have access to that inbox and therefore own the email address they registered with.
Unfortunately, the Click To Pray API also returned the validation hash in its response when someone clicked the verification link. These responses are easy to inspect using a web browser’s developer tools, meaning an attacker could register an account using an email address they didn’t control and verify it before the real owner even saw the verification email.
Six months, nine contacts, zero replies
BobDaHacker first reported the bug on January 3, 2026, eventually emailing nine addresses spanning the Click To Pray service, the Pope’s Worldwide Prayer Network, and a general information address. They got no response. It was only fixed more than six months later after the researcher contacted a journalist, who filed a query with the Vatican.
Responsible disclosure only works when the recipient has a functioning intake process. Nine unanswered emails were a strong signal that no such process existed.
Not the first security flaw in a Vatican app
This isn’t the first security flaw involving a Vatican app. In 2019, UK firm Fidus Information Security found a flaw in the app for the Vatican’s Bluetooth eRosary device. It didn’t use a conventional password for logins. Instead, users entered their email address and the app sent a four-digit PIN to that address. They then entered the PIN to log in.
However, when the user entered their email address, the app also returned the PIN in plain text in its web response. That enabled an attacker to take over anyone’s account simply by inspecting the response.
That flaw was similar to the account verification issue that BobDaHacker discovered more than six years later. Although the incidents involved different apps, they show how the same type of security mistake can reappear years apart.
BobDaHacker also noted that Vatican City State introduced its own data protection regulation, Decree No. DCLVII, on April 30, 2024. The regulation requires appropriate safeguards for personal data. However, it’s not clear whether it applies directly to Click To Pray or the organisations that operate it.
What users can do now
Thankfully, someone on the Vatican side has now fixed the flaws, but the vulnerability meant that user data was exposed for a long time. If you registered an account, assume your email, name, date of birth, and country are potentially in circulation. Watch for phishing that references the app, and be especially skeptical of messages claiming to come from Vatican-affiliated services asking you to click, verify, or log in.
This is particularly important because BobDaHacker also reported that emails from the service failed standard email authentication checks. These checks help receiving email providers verify that a message really came from the domain it claims to represent. According to the researcher, this could make it easier for phishing attackers to impersonate the organisation.
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