Mozilla released an emergency update for Firefox on March 7th, 2013 with versions 17.0.4esr and 19.0.2 to desktop users. This release addresses issues in regards to security advisory MFSA 2013-29. Mozilla also released Firefox 19.0.1 back on February 27th, 2013 to Windows 8 users only to address stability issues with some AMD Radeon HD Graphics cards.
Depending on their update settings (Tools > Options… > Advanced > Update Tab), users will be prompted to update within in the next 48-hours. Users can also go to Help > About Firefox and click the Check for Updates button or go to getfirefox.com and manually download and install Firefox.
The next scheduled releases for Firefox are Firefox 20.0.0 and Firefox 17.0.5esr on April 2nd, 2013.