The incident occurred during the government shutdown, which has reduced the operational capacity of CISA, the national cybersecurity agency.
The Washington Post revealed on November 6, 2025, that a “foreign actor” had hacked the Congressional Budget Office (CBO), a nonpartisan agency responsible for drafting economic projections for lawmakers. Federal authorities warned members of Congress by email, urging them to remain highly vigilant and stating that the incident was still “ongoing.”
The cyberattack took place in the midst of the shutdown, which has been in effect for a month. This freeze on government budgets has forced CISA—the U.S. equivalent of France’s ANSSI—to place two-thirds of its employees on unpaid leave.
The CBO assesses the potential financial impact of each bill reviewed by the Senate or the House of Representatives, handling sensitive political and economic data. According to a source close to the matter cited by CNN, investigators suspect that a group linked to China was behind the attack.