An infectious worm is spreading on Tumblr Monday morning, affecting several major blogs.

Tumblr spokesperson Katherine Barna sent the following email to Mashable regarding the worm:

"There is a viral post circulating on Tumblr which begins 'Dearest 'Tumblr' users.' If you have viewed this post, please log out of all browsers that may be using Tumblr immediately. Our engineers are working to resolve the issue as swiftly as possible."

Update: According to a follow-up email from Tumblr received at 1:28 p.m. ET, "Tumblr engineers have resolved the issue of the viral post attack that affected a few thousand Tumblr blogs earlier today."

While Tumblr remains online, posting is currently disabled. A pre-emptive password reset is probably a good idea for any Tumblr user reading this post. The truly cautious may wish to avoid Tumblr entirely until the mess is sorted out.

The worm seems to be infecting any account that either reblogs or views (on an individual blog, not on users' dashboards) the insulting post seen below.

Mashable reader Christian H. shared a screenshot showing the post activates a fake pop-up, which if clicked allows the worm to spread. If you encounter the pop-up, do not click any part of it — instead, kill your browser immediately with Task Manager or your operating systems' equivalent.

Once a blog is infected, the post is then continuously reposted by infected users' accounts. The worm is from the GNAA, a well-known hacker and Internet trolling collective. GNAA claims to have infected more than 8,000 Tumblr blogs as of late Monday morning.

The text of the post:

Dearest `Tumblr’ users, We have taken the liberty of upgrading your (rather tasteless, we must say) blog to our premier GNAA Deluxe Gary Niger (pictured to the left) Signed Edition! This is in response to the seemingly pandemic growth and world-wide propagation of the most FUCKING WORTHLESS, CONTRIVED, BOURGEOISIE, SELF-CONGRATULATING AND DECADENT BULLSHIT THE INTERNET EVER HAD THE MISFORTUNE OF FACILITATING. However, we do not believe you are beyond redemption! All you have to do is DRINK BLEACH AND DIE YOU EMO, SELF-INSISTING, SELF-DEPRECATING, SELF-INDULGENT EMPTY HUSKS OF HUMAN BEINGS. REPEAT AFTER ME: I WISH I WAS PROFOUND, BUT I’M NOT! I WISH I WAS ORIGINAL, BUT I’M NOT! I WISH MY IMPENDING DEATH WAS OF ANY CONSEQUENCE, BUT IT IS MOST CERTAINLY NOT! Your last chance for redemption hinges upon your death; your death which was most fortunately prescribed by your most unfortunate birth. Fret not, dear emo, your death will be regarded as a sacrifice to humanity; to die a martyr is a glorious death, and will likely be your highest contribution to society. SHOUTZ: LITERALKA - DOLPHIN/DZL - BERRY/BRR - RORY - INFID3L - INCOG P.S. Attempting to delete these posts will delete your tumblr account ;] But, by all means, go ahead!

HyperVocal and The Verge are among those that have been hit:

This writer, too, was struck by the bug. However, a rapid password change and deletion of the infectious posts seems to have cured my personal account of any ill effects.

Have you been struck by the bug? Share your story in the comments.

Mashable composite. Images courtesy of iStockphoto, empato, SoupGFX, and NASTCO.