Also called fixes or bug fixes. Corrections to existing programs, designed to be integrated into the programs without major release changes. Patches or fixes to voting systems must be tested before being applied, and may invalidate certifications. Do not install software patches without extensive technical review for unintended consequence.
Source: The State and Local Election Cybersecurity Playbook, Defending Digital Democracy Project, Harvard Kennedy School Belfer Center for Science and International Affairs, https://www.belfercenter.org/sites/default/files/files/publication/StateLocalPlaybook%201.1.pdf; Information Technology Terminology, U.S. Election Assistance Commission, https://www.eac.gov/documents/2017/09/21/information-technology-terminology-security