Open-source software security is the set of practices used to protect freely shared code from bugs, abuse, and supply-chain attacks. Because open-source projects are reused across servers, apps, and embedded systems, a single weakness can spread widely through downstream software.
Defenses include code review, secure dependency management, signed releases, vulnerability disclosure, patching, and reproducible builds. Maintainers also use issue triage to separate real exploit paths from low-risk findings, which helps limited teams focus on the fixes that matter most. Attackers target open-source ecosystems by planting malicious packages, hijacking maintainer accounts, or slipping backdoors into popular libraries. Strong open-source security reduces that risk by making it harder to tamper with code, easier to verify updates, and faster to respond when flaws are found.