SAN FRANCISCO — Glassdoor Inc., the operator of the anonymous job review website, is facing down a massive class action after inadvertently revealing the email addresses of hundreds of thousands of users by failing to “blind CC” recipients on a mass email.

The Sausalito, California-based company was sued Monday afternoon in a Los Angeles federal court by attorneys at Geragos & Geragos who argue that the company endangered the jobs of users whose email addresses were exposed by mistake on July 22.