The United States government erroneously shared the Social Security numbers of more than 1,900 people online earlier this year, part of a data breach that occurred during the publication of the Jan. 6 select committee report, according to a letter reviewed by The Washington Post.

The "Notice of Data Breach" apology letter from the U.S. Government Publishing Office said Social Security numbers were published online for about two days in January 2023, and that the government breach affected more than 1,900 people who visited the White House on a particular day in December 2020 and whose identities appeared on visitor logs obtained by the Jan. 6 committee.

"I share your concern and frustration that this occurred," wrote Hugh Nathanial Halpern, the director of the Government Publishing Office.

According to the letter, those affected by the breach visited the White House on Dec. 14, 2020. The logs - without redactions of Social Security numbers and other personal information - were published online from Jan. 2 to Jan. 4 this year, according to the apology letter.

It is unclear who was responsible for the lack of redactions, and the letter does not say how the government discovered the data was online.

The letter was dated March 24, and it arrived this week, according to a person who received it. Another visitor to the White House, who spoke on the condition of anonymity to share the letter, said he was angry that it arrived almost three months after the breach was discovered.

The breach included information about top Republicans and other prominent Americans who visit the White House. Many of those involved in the breach were people attending a Christmas party, people familiar with the matter said.

The government obtains the personal information to vet visitors who step onto the highly protected complex. Generally, the lists of visitor names, minus the sensitive personal data, is released by administrations, though the Trump White House declined to make its list of visitors publicly available.

The logs, which were "supporting materials" for the final committee report, were provided to the Government Publishing Office by the Jan. 6 committee, which obtained the logs from the National Archives, according to the letter sent.

But no one redacted the Social Security numbers from the report, the letter says.

A different version of the data without Social Security numbers then was published for about a month, before a "much more limited" version was published in February, the letter says.