Twitter security issues in 2020 is said to have already been reported to the company’s business customers such as advertisers warning about the possibility of their information been compromised. Twitter furthered by stating that business users’ billing information which was inadvertently stored in browser’s cache might have been accessed by those who share computers.

Other important data includes business user’s email address, their phone numbers and the last four digits of their credit card number which is associated to their account. The social media company told users that it first became aware of the problem back in May 20th which is a month right after it disclosed a similar bug that improperly stored user data such as direct messages in Firefox’s browser cache.

Twitter spokesperson Laura Pacas confirmed the incident to TechCrunch, but declined to disclose the number of people affected.

“We became aware of an incident where if you viewed your billing information on ads.twitter.com or analytics.twitter.com the billing information may have been stored in the browser’s cache,” the spokesperson said. “As soon as we discovered this was happening, we resolved the issue and communicated to potentially impacted clients to make sure they were aware and informed on how to protect themselves moving forward.”

It’s one of the latest security issues in 2020 and last year, the company was able to track a bug which was exposed phone numbers associated with millions of Twitter accounts. The bug also gave account location data to one of it’s partners.

Twitter last year also said it used phone numbers provided by users for two-factor authentication for serving targeted ads. In 2018, Twitter admitted it stored user passwords in plaintext, and warned its millions of users to reset their passwords.