Apple says it is working to fix a bug that can cause devices to crash.
It responded to reports of apps becoming unresponsive by confirming that some versions of its operating systems were hit when a single character in Telugu, one of four official languages in India, was sent to the device or typed.
Apple said that a fix was needed for iOS 11, macOS High Sierra, watchOS 4 and tvOS 11 but insisted older versions were not affected.
The bug marked another hurdle for the company following a string of software problems - blamed by experts on a fast-paced release cycle that meant flaws were being left in code by programmers.
Just last month Apple was forced to release software updates to patch processor flaws, known as Meltdown and Spectre, that left users potentially vulnerable to hackers.
The latest bug was first spotted by the Italian blog Mobile World.
According to tech news website The Verge, apps including Apple's iMessage and third-party applications like WhatsApp, Gmail and Facebook messenger crashed when Telugu was used or appeared.
However, other apps including Skype seemed to be unaffected.