Mozilla announced on Tuesday that a Firefox exploit has been discovered in the wild. The exploit affects Windows, Linux, and Mac users, and Mozilla has issued a patch. If you're a Firefox user, TMO recommends you update immediately.
The exploit was deloyed on a Russian news site in the form of a maliciously crafted ad. The code in the ad was able to search for local files and then upload them to a remote server "that appears to be in the Ukraine."
The files the exploit looked for were developer-related files, as well as local password files. For Mac users, the exploit would look for history files, password files, and others.
If a user did encounter the malware, Mozilla said it leaves no trace of its activities.
You can find update instructions on the Mozilla site.