The global Microsoft CrowdStrike outage, explained

Airline travel, banking, and other public and private services were in disarray when a CrowdStrike cybersecurity software update caused computers to crash worldwide. “This is basically what we were all worried about with Y2K, except it’s actually happened this time ☠️,” Troy Hunt, an Australian cybersecurity expert and tech consultant, wrote on X.

CrowdStrike, used by over half of all Fortune 500 companies, deployed a Falcon Sensor software update overnight on July 18, 2024. That update, related to secure file storage in the cloud, caused Windows to present the “Blue Screen of Death” to users, which brought many businesses and crucial public services to a standstill.

The problem related to how CrowdStrike, running at the “kernel” level of a computer interacts with the operating system, and Windows machines were affected in particular. Mac and Linux computers had no issues, according to CNN.

CrowdStrike CEO George Kurtz said what happened was not a cyberattack or a security incident. “CrowdStrike is actively working with customers impacted by a defect found in a single content update for Windows hosts … The issue has been identified, isolated and a fix has been deployed,” Kurtz said.

Here’s a close look at the banks and airlines affected by the outage.

Which airlines have been affected by the outage?

Amid the outage, air travel was in chaos at many major U.S. and international airports, leaving the airport and airline staff scrambling to accommodate stranded travelers. “The FAA is closely monitoring a technical issue impacting IT systems at U.S. airlines. Several airlines have requested FAA assistance with ground stops until the issue is resolved,” the FAA said in a statement on X.

Delta and United had resumed flights as of noon Friday, July 19, but warned of potential delays and cancelations. Though affected, American Airlines recovered and was able to reestablish its operation. Budget airlines SunCountry, Allegiant Air, Frontier, and Spirit Airlines had not yet resolved the issue. Mexico’s Volaris and Viva Aerobus were also impacted. Canada’s Porter Airlines canceled all flights until noon Friday. Southwest Airlines was unaffected, according to CNN.

International air travel was also affected as airlines in Australia, India, Asia, Europe, and the Middle East faced similar issues. “We’re continuing to address effects on transportation systems from today’s widespread tech outage. Many flights are impacted as systems recover — passengers should check with their airline for updates and visit our website for more on passenger protections,” the U.S. Secretary of Transportation Pete Buttigieg wrote on X.

Which banks have been affected by the outage?

Beyond the airline industry, many banks and financial institutions were hit by the CrowdStrike issue, including Arvest Bank, Bank of America, Capital One, Charles Schwab, Chase, TD Bank, US Bank, and Wells Fargo, according to Downdetector. “TD and other organizations around the world have been impacted by a global technology disruption. Teams are working hard to restore all online banking and other impacted systems. For immediate banking needs, TD customers can visit their local TD bank or fully operational ATM. We thank you for your patience,” a TD Bank spokesperson told Newsweek in a statement.

As of Friday afternoon, many organizations were still addressing the problem, but some had not yet recovered. Still, it was widely reported that delays and other disruptions should be expected and that it could take some time before the CrowdStrike outage was resolved. Affected devices, including servers, will have to be manually rebooted by an administrator, and the CrowdStrike update will have to be deleted by hand, according to CNN.