Does CMake/make have the ability to make my Linux operating system unstable?

No. (or: as long as you don't run it as root, nothing should affect your operating system. As Stephen points out, things you run as your user could modify your user's data. It's just that CMake's job specifically is to contain everything it does to a single directory of your choosing. You can of course still make CMake invoke some other functionality that messes with your system. But seeing that, CMake is as "dangerous to your system's stability" as, say, a text editor, with which you could of course damage your desktop environment's settings files so that things don't work anymore. But unless you take specific steps to make that happen, it won't happen.

There's an installation step, which job it is particularly to put files where you told CMake to put them; if you decide to put them where they would overwrite system things, and run the installation tool as root, I'll argue it's not CMake that makes your system unstable, it's you ;) )

Or that, if I dared attempting to run my CMake command with a sudo, this could happen.

that being necessary would just be an indication of you doing something wrong when writing your CMake scripts. CMake is especially designed for not needing root privileges.

(this isn't specific to CMake. Generally, project configuration utilities of the last 20 to 30 years are written so that a project can be configured and software be built without root privileges.)

Does CMake/make have the ability to make my Linux operating system unstable?

No. (or: as long as you don't run it as root, nothing should affect your operating system. As Stephen points out, things you run as your user could modify your user's data. It's just that CMake's job specifically is to contain everything it does to a single directory of your choosing. You can of course still make CMake invoke some other functionality that messes with your system. But seeing that, CMake is as "dangerous to your system's stability" as, say, a text editor, with which you could of course damage your desktop environment's settings files so that things don't work anymore. But unless you take specific steps to make that happen, it won't happen.

There's an installation step, which job it is particularly to put files where you told CMake to put them; if you decide to put them where they would overwrite system things, and run the installation tool as root, I'll argue it's not CMake that makes your system unstable, it's you ;) )

Or that, if I dared attempting to run my CMake command with a sudo, this could happen.

that being necessary would just be an indication of you doing something wrong when writing your CMake scripts. CMake is especially designed for not needing root privileges.

(this isn't specific to CMake. Generally, project configuration utilities of the last 20 to 30 years are written so that a project can be configured and software be built without root privileges.)

and where I was figuring that the underlying make scripts could be able/willing to put their .so binary to /usr/local/bin or to some place where it could attempt to replace the binary currently used by my Debian 12.

Yeah, here someone that shouldn't have been given root privileges on their machine was doing something stupid. Not your fault, neither make or CMake's (these are pretty different tools, right), you can perfectly well build dependencies for a CMake project internally without trying to install them globally. It would seem that "subproject" needs your fixing :(

Does CMake/make have the ability to make my Linux operating system unstable?

No.

Or that, if I dared attempting to run my CMake command with a sudo, this could happen.

that being necessary would just be an indication of you doing something wrong when writing your CMake scripts. CMake is especially designed for not needing root privileges.

(this isn't specific to CMake. Generally, project configuration utilities of the last 20 to 30 years are written so that a project can be configured and software be built without root privileges.)

Does CMake/make have the ability to make my Linux operating system unstable?

No. (or: as long as you don't run it as root, nothing should affect your operating system. As Stephen points out, things you run as your user could modify your user's data. It's just that CMake's job specifically is to contain everything it does to a single directory of your choosing. You can of course still make CMake invoke some other functionality that messes with your system. But seeing that, CMake is as "dangerous to your system's stability" as, say, a text editor, with which you could of course damage your desktop environment's settings files so that things don't work anymore. But unless you take specific steps to make that happen, it won't happen.

There's an installation step, which job it is particularly to put files where you told CMake to put them; if you decide to put them where they would overwrite system things, and run the installation tool as root, I'll argue it's not CMake that makes your system unstable, it's you ;) )

Or that, if I dared attempting to run my CMake command with a sudo, this could happen.

that being necessary would just be an indication of you doing something wrong when writing your CMake scripts. CMake is especially designed for not needing root privileges.

(this isn't specific to CMake. Generally, project configuration utilities of the last 20 to 30 years are written so that a project can be configured and software be built without root privileges.)