From the New York Post:
The IRS mistakenly posted the Social Security numbers of tens of thousands of Americans on a government website, the agency confirmed Monday night. One estimate put the figure as high as 100,000 names.
The numbers were posted to an IRS database for tax-exempt political groups known as 527s and first discovered by the group Public.Resource.org.
The California-based group said it learned of the "privacy breach" Tuesday while working on an unrelated audit of an “improperly vetted shipment” of IRS data on DVDs and promptly informed the agency, which shut down the site the next day.