Apple is warning about a security issue for iOS 13 users who installed certain keyboard apps.

A bug can give third-party keyboard apps, such as Microsoft-owned SwiftKey or Google's Gboard, unexpected access to people's phones. That "can result in keyboard extensions being granted full access even if you haven't approved this access," Apple said in a statement released Tuesday.

Some third-party keyboard apps can operate as a "standalone," meaning they don't need full access to a users' phone. Those apps and Apple's pre-installed keyboards aren't not affected by this issue, the company said.

Apple said the security issue affects iPhone, iPad and iPod touch owners that use the newly released iOS 13 operating system. Apple said the issue will be fixed in an upcoming software update, but didn't reveal exactly when.

It's the second security issue with iOS 13 in a week. Another flaw with the operating system exposed contact details stored in iPhones without requiring a passcode or biometric identification. The company released a fix for the issue on Tuesday.