MPs and journalists have had their phone numbers, email addresses and personal details revealed on the Tory Party Conference app.
A Guardian columnist highlighted the security breach on Twitter, where she said she was able to access the personal details of Boris Johnson.
The BBC has also been able to access private information of attendees, but the problem has since been rectified.
The Conservative Party has been approached for comment.
BBC political correspondent Chris Mason said the technical glitch was "deeply, deeply embarrassing" for the party.
Dawn Foster, who is attending the conference, tweeted about the security breach and said she had been able to access the former foreign secretary's personal details, including his mobile phone number.
It appears that people could access an MP's personal details by entering their email address, without a password, when pressing the attendee's button in the app.
This button has since been removed.