Union claims hackers hit all federal employees

Scale of govt. security breach 'stunning'
Vantiv's enhanced electronic security
VENOM security bug threatens cloud

A federal employee union says hackers stole personnel data and Social Security numbers for every federal employee, charging that the cyberattack on federal employee data is far worse than the Obama administration has acknowledged.

Read More Up to 4 million exposed in deep federal data breach

Sen. Harry Reid, the Democratic leader, said on the Senate floor that the December hack into Office of Personnel Management data was carried out by "the Chinese." Reid is one of eight lawmakers who is briefed on the most secret intelligence information.

J. David Cox, president of the American Federal of Government Employees, said in a letter to OPM director Katherine Archuleta that based on OPM's internal briefings, the hackers stole military records and veterans' status information, address, birth date, job and pay history, health insurance, life insurance, and pension information; age, gender, race data.

A spokesman for OPM told NBC News that the union's charge that every federal worker's data was part of the hack is not true. He said the government has not changed its position on the numbers originally reported last week: 4.2 million people were affected, including 1 million retirees, 2.1 million active civilian federal workers and 1.1 million separated workers.

Read MoreObama: US cybersecurity problems will get worse

The OPM spokesman told NBC that the union conflated its numbers, and that OPM does not include records for active military personnel or Congressional employees.

—NBC News and CNBC's Everett Rosenfeld contributed to this report.