An open-source project is software whose source code is publicly available, usually under a license that allows anyone to inspect, modify, and redistribute it. These projects are often built and maintained by small teams or volunteers, which makes code review, testing, and patching dependent on limited human capacity.
In cybersecurity, open-source projects matter because they are both widely trusted and widely exposed. Attackers may study the code to find bugs, weak authentication, unsafe dependencies, or memory-safety flaws. Defenders also rely on open-source code for the same reason: visibility makes it easier to audit, scan, and fix. Security tools, bug bounty programs, and AI-assisted review can uncover issues at scale, but the real challenge is remediation. A project may receive more vulnerability reports than maintainers can quickly verify and patch, so good disclosure handling, dependency tracking, and release discipline are essential.