Adobe patched a trio of vulnerabilities in Flash Player, two of which the company says hackers were already exploiting in attacks targeting Mozilla Firefox.

The emergency update to Flash Player comes as the third emergency fix for the browser plug-in this month, and patches holes that could not only cause a crash, but could potentially allow attackers to take over an affected system.

In the accompanying security bulletin, Adobe confirmed it was patching three vulnerabilities in the popular Flash media player plug-in. According to the company, attackers were already exploiting two of those vulnerabilities.

"Adobe is aware of reports that CVE-2013-0643 and CVE-2013-0648 are being exploited in the wild in targeted  attacks designed to trick the user into clicking a link which directs to a website serving malicious Flash content," states the advisory, listing the vulnerabilities by Common Vulnerabilities & Exposures (CVE) identifiers. "The exploit for CVE-2013-0643 and CVE-2013-0648 is designed to target the Firefox browser," adds the company.

Consequently, the two vulnerabilities Adobe singled out are in fact "zero-day" vulnerabilities, which means that criminals have already exploited them with attack code before updates patched the bugs.

The emergency updates, on Tuesday, Feb. 26, come less than three weeks after a Feb. 8 fix for two flaws exploited in the wild. The company already issued two other regularly scheduled updates for Flash since the beginning of 2013, as part of its efforts to sync its security releases with Microsoft's monthly Patch Tuesdays.

"Adobe assigned a Priority 1 rating to the vulnerabilities exploited on Windows and Mac OS X and recommends that users of both operating systems install the updates as soon as possible, preferably within 72 hours. The bulletin also assigned a Priority 3 rating to a Flash vulnerability facing Linux users.

The Priority 1 rating is Adobe's highest threat level, identifying "vulnerabilities being targeted or which have a higher risk of being targeted, by exploit(s) in the wild."

Users can download the patched versions of Flash Player for Windows, Mac and Linux from Adobe's website. Windows and Mac users can also wait for Flash's automatic updating tool to grab the update, while users of Google Chrome and Microsoft's Internet Explorer (IE) 10 on Windows 8 will receive the newest Flash via the browsers' own update mechanisms.