Security fault allows hackers to send text messages that can reboot device and damage software.
Windows Phone 7.5 otherwise known as Mango, was launched a couple of months ago boasting more than 500 new features.
However, it's probably safe to assume that the bug wasn't supposed to be one of them.
The flaw was revealed by WinRumours when a reader unearthed the potential threat and alerted the site of the dangers.
WinRumors proceeded to test the glitch across devices including HTCs and Samsungs to find that malicious text messages can reboot the handset to damage the messaging hub feature.
As this happened to both handsets, it means the bug isn't down to the device but the way that Windows Phone handles messages. The site confirmed that Facebook chat messages and Windows Liver Messenger can also receive the bug.
In a statement given to The Verge, Greg Sullivan, Windows Phone senior product manager, said: "We are aware of the issue and our engineering teams are examining it now. Once we have more details, we will take appropriate action to help ensure customers are protected."
We recently reported that Samsung experienced issues following the UK launch of its Galaxy Nexus, which has sound issues as well as a fault with it's 2G signal.