Linux is an open-source operating-system kernel: privileged software that manages hardware, memory, processes, filesystems, and networking. Most deployments use it through a distribution that adds user-space tools, package managers, libraries, and an update policy. This distinction matters in security reporting: a kernel flaw, a distribution-package flaw, and a flaw in an application running on Linux may have different affected versions and fixes.
Material attack surfaces include kernel code, loadable modules and device drivers, network services, local privilege boundaries, and third-party packages. Vulnerabilities can enable denial of service, information disclosure, or escalation from an unprivileged account to root, depending on configuration and exploitability. Administrators should track upstream and distribution advisories, apply security updates, and reboot when a running kernel remains vulnerable. Mandatory access-control systems such as SELinux or AppArmor can restrict compromised processes; signed repositories, audit logs, and tested configuration baselines support package integrity and investigation. Open source does not itself guarantee security: exposure depends on code, configuration, maintenance, and the surrounding software stack.