The glitch affects the People app, which stores all contact information, making it impossible to add significant dates such as birthdays that fall in the final month of the year.
"Rest assured, this will be fixed soon so that those of you with December birthdays and anniversaries won't be forgotten by your friends and family," said Google in a statement.
Google is expected to correct the issue with an over-the-air update before the end of the month, giving it just over a week to roll out the fix.
Android 4.2 is a refreshed version of the Ice Cream Sandwich operating system that launched with the Nexus 4 and Nexus 10 devices earlier this month.
Google's next mobile operating system, the rumoured Android 5.0 Key Lime Pie, has been tipped to launch with a flagship Sony smartphone next year.