Information about the flaw, which was discovered earlier this year, was shared with Google in February 2013, and has already been fixed. But the main problem is that device manufacturers and carriers are unlikely to be very prompt in pushing out patched Android versions to users, and users of older devices already don't receive receive security updates.
The good news is that the bug hasn't, so far, been spotted being exploited in the wild, but that might soon change as security researcher Pau Oliva published has proof-of-concept code that can exploit it.
Oliva, who is a mobile security engineer at viaForensics, says that he has created the POC after reading details about the bug in a publicly available Cyanogenmod report. The developers of the popular modified Android firmware have already pushed out a patch for it.
According to The Register, the POC doesn't insert malware into the target code - it just allows an app pose as another one. Nevertheless, the information is now out there, and device manufacturers and carriers should now consider quickly shipping out patches for it.