A small Syracuse stationary company wanted to hold a contest on Pinterest for its customers. Instead, it’s been inundated with spam—and is helpless to do anything about it.

Bella Figura Letterpress invited more than 180 Pinterest users to pin to its Do Good in March collaboration board. However, a glance at the board reveals just one good deed … and multiple photos of random affiliate links from spammers.

Since Pinterest doesn’t give the owner of a collaboration board special privileges, the small business can’t remove these spam links without Pinterest’s help. And Pinterest isn’t helping.

Bella Figura wrote:

“We reported these on Friday morning, just after they started appearing, and also removed the spammers from this board. The pins haven’t disappeared yet. In fact, more have appeared. Sad … but hopefully Pinterest will get this under control. We’re hoping to make this board more uplifting but need their cooperation!”

Pinterest’s collaboration option is supposed to make it easy to pin to a board with multiple contributors. However, holes in the feature make it a prime tool for exploitation.

The Daily Dot has already covered the ways that you can use collaboration boards to hijack big name pinners, including the President. Simply add these big names to your shared boards. Since Pinterest won’t wait for their consent first, it will appear as if these users are promoting your boards.

Now, we’ve discovered a new loophole that shows hijacking can go both ways. Pinthusiast Claire Isabel Hutchinson tipped us off to how Bella Figura’s shared board was rendered a spam free-for-all.

“I am guessing a lot of people haven’t thought about how to really run a competition on Pinterest or the problem of letting people pin on your board!” Hutchinson told the Daily Dot. “You cannot remove the pins that are pinned by another contributor on a board that you set up and let others contribute to.”

More experienced Pinterest users are already aware of the problem. Drew Hawkins, the founder of Board of Man, has 200,000 followers for his board, butonly 26 contributors, all of whom he knows personally. To keep things under control, he invites strangers to tag their own pins with #menofpinterest to get his attention.

Likewise, Modcloth, an online retailer of women’s vintage clothing, allows users to email pins to their Guest Pinner Gallery instead of joining it outright.

Some brands have already discovered a spam-free option for holding a contest. Instead of inviting users to pin to the brand’s board, it asks users to design and submit their own boards to the contest. Better Homes and Gardens and Lands End have both embraced this approach.

As Pinterest only gets larger, spammers are becoming more of a problem. Online security firm Trend Micro’s TrendLabs lists a few of Pinterest’s most popular scams on its Malware Blog. If you see a pin that looks too good to be true, click the “Report Pin” button on the side of the image.