Twitter is urging users to change their passwords after discovering a bug in its system that left passwords exposed.

“We recently found a bug that stored passwords unmasked in an internal log. We fixed the bug and have no indication of a breach or misuse by anyone. As a precaution, consider changing your password on all services where you’ve used this password,” Twitter tweeted on Thursday.

In a blog post, Twitter explained that it “masks” passwords through a process called “hashing” that replaces the actual password with a random set of numbers and letters. These are then stored in Twitter’s system.

TWITTER SUFFERS OUTAGE AS USERS AROUND THE WORLD EXPERIENCE PROBLEMS

The hashing process, which is widely used in the tech industry, lets Twitter validate users’ account credentials without revealing their passwords.

“Due to a bug, passwords were written to an internal log before completing the hashing process,” Twitter said, in a statement. “We found this error ourselves, removed the passwords, and are implementing plans to prevent this bug from happening again.”

Follow James Rogers on Twitter @jamesjrogers