The US government shutdown, which began on October 1, 2025, has triggered significant concerns regarding the nation's cybersecurity posture, primarily due to the expiration of the Cybersecurity Information Sharing Act (CISA) of 2015 and the reduction in cybersecurity personnel. This confluence of events has created security gaps and uncertainty for both businesses and government agencies.

Expiration of Key Cyberthreat Sharing Law

The lapse of the Cybersecurity Information Sharing Act of 2015 is a major concern. This law provided legal protections for companies to share cyber threat information with the federal government, encouraging them to report breaches and threats without fear of liability. With the expiration of CISA 2015, US companies no longer have this legal shield, potentially deterring them from sharing critical cyber threat intelligence. Senator Gary Peters described the lapse as "an open invitation to cybercriminals and hostile actors to attack our economy and our critical infrastructure". The absence of this law can lead to decreased information sharing by private entities, complicating the security landscape.

Impact on CISA and Federal Cybersecurity Efforts

The government shutdown has significantly impacted the Cybersecurity and Infrastructure Security Agency (CISA), the primary agency responsible for defending government networks and critical infrastructure. Due to the shutdown, CISA is operating with a significantly reduced workforce, with approximately 65% of its employees furloughed. This translates to a loss of over 1,600 personnel, leaving the agency with only around 900 employees to handle cybersecurity threats.

This reduction in staff has several implications: * Diminished capacity to analyze and track cyber threats: A smaller workforce means fewer resources available to monitor emerging threats, conduct vulnerability assessments, and coordinate responses to incidents. * Slowed or halted projects: Federal resources, including projects at CISA, may be slowed or not entirely halted. Longer-term cybersecurity projects are likely to be pushed aside as staff prioritize immediate fixes. * Erosion of threat intelligence development and distribution: An extended shutdown could erode CISA's ability to develop or distribute threat intelligence. * Increased vulnerability to attacks: Some CISA employees are concerned that hackers might exploit the reduced staffing to slip through federal agencies' digital defenses.

Increased Cyberattack Risks

Security experts warn that the combination of the expired law and the depleted cybersecurity workforce creates an environment ripe for exploitation by cybercriminals. The shutdown occurs as cyberattacks on infrastructure providers have surged globally, with ransomware and supply chain attacks growing more sophisticated. Potential consequences include:

• Phishing attacks targeting furloughed workers: Furloughed federal workers are particularly vulnerable to phishing attacks targeting their credentials, especially those related to HR and benefits communications.
• Exploitation of security gaps: Cybercriminals may exploit critical security gaps to launch attacks, including targeting the government's networks and critical vulnerabilities.
• Compromised incident response: Limited staffing and operational restrictions impede the ability to coordinate rapid responses to cyber incidents.

Impact on Businesses and State/Local Agencies

The cybersecurity implications of the shutdown extend beyond the federal government. Government contractors may face budget cuts and missed paychecks, potentially leading to decreased cybersecurity investments. State and local cybersecurity officials also feel the effects of the shutdown, especially with the expiration of state cybersecurity grant programs. Reduced federal support may lead to a surge in cyberattacks on local agencies, and leaders are urged to prepare for potential breaches using only state and private resources.

Potential Long-Term Effects

The cybersecurity impact of the shutdown is likely to last beyond the period of the shutdown itself. Delays in projects, stalled timelines, and funding pauses can have ripple effects across planned cyber and IT efforts. There are also concerns that the shutdown will have lasting effects on interest in government cybersecurity positions.

Responses and Mitigation

Despite the challenges, some cybersecurity firms have pledged to continue sharing threat data. Experts recommend that companies rely on private or standards-based cybersecurity approaches, protect core assets, and diversify their defense approaches.