Mozilla Messaging patched nine security vulnerabilities in Thunderbird Wednesday, the first time it's plugged holes in the e-mail software since early May.

Thunderbird 2.0.0.16, which was added to Mozilla's download servers late Wednesday, quashes nine bugs, including one that was patched last week in Firefox , the company's open-source browser. The remainder fix flaws that were first addressed in early July when Mozilla updated Firefox to version 2.0.0.15.

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It's not unusual for Thunderbird security updates to lag behind those released for Firefox.

Seven of the nine bugs were rated "moderate" by Mozilla, the second-lowest of the four rankings in its threat system. The other two were pegged as "low."

The bug patched in Thunderbird Wednesday that was fixed in Firefox last week was in the browser rendering engine's CSSValue array data structure. According to Mozilla, the vulnerability could be used by hackers to force a crash, and from there, run malicious code. Several other just-patched Thunderbird vulnerabilities could also be used by attackers to execute code remotely.

Thunderbird 2.x, like its browser sibling, is on the way out. Most of Mozilla's attention is now on Thunderbird 3.0, which has been available as an Alpha 1 preview for more than two months.

Users can download Thunderbird 2.0.0.16 in versions for Windows, Mac OS X, and Linux from the Mozilla site, call up the e-mail client's built-in updater or wait for the automatic update notification, which typically appears within 24 to 48 hours.