According to USA Today, employers are sharing millions of these records with outside companies, which in turn make them available to landlords, bankers and others.
In fact, reports the paper, companies such as Walgreen and Boeing are so bogged down with requests that they have turned to firms specializing in employment verification.
Those firms now have more than 28 million records, or data for about a fifth of the U.S. workforce.
The information is supposed to be given out only with your authorization, but privacy experts worry there's potential for abuse.
"The concern is that here is one more giant database," says William Hubbartt, author of The New Battle Over Workplace Privacy. "What if a hacker gets in or someone is careless in how the information is used?"
Employees generally can't keep their employers from sharing the data, but they can have information blocked so it won't be shared with others.
"Several companies also come in on an annual basis and do a security audit," says Bill Canfield, CEO and president of TALX, a firm that has more than 400 employers and 27 million records.
That may not be enough, say critics.
"Just the fact salary is in a database is uncomfortable," says Lewis Maltby of the American Civil Liberties Union. "Eventually, all databases leak."