The Linux kernel remains one of the best engineered and most scrutinized operating-system kernels out there, but secure is relative.
It depends heavily on which version we are running, how quickly we apply updates, which configuration and modules our system uses, and how exposed the system is.
Linux kernel security is relatively strong today.
The Linux kernel has a very large and active developer community.
Many bugs, memory safety issues, driver faults, and other problems are found and fixed quickly.
Modern kernels get frequent updates and patches, both for bugs and for security issues, and upstream kernels (as distributed by kernel.org) tend to get security fixes promptly.
For many common use cases (desktop, trusted servers, well-maintained distributions), keeping the kernel updated provides a strong baseline defence.
Some serious recent kernel vulnerabilities have been discovered, but they are generally patched once found, which shows the system is actively maintained.
In short, if we use a reasonably recent kernel, apply security updates promptly, and avoid risky configurations (untrusted third-party drivers, exposing root or admin privileges indiscriminately), the Linux kernel remains at the high end of OS security.
Enjoy #linux
Well, that was exciting. See you in the next one!