Starting with this commit, as can be seen in buildbot here, Connector/C builds started failing the zlib portion of the cmake CPack steps when creating the tar.gz binary packages.

From the output of the build logs it looks like the CPack packaging steps are trying to write to /usr/local/lib , /usr/local/include , and other directories like it is doing a "make install" instead of a "make package".

Here's an example build log: https://buildbot.mariadb.net/buildbot/builders/cc-bullseye-amd64/builds/95/steps/compile/logs/stdio

The only way to work around this seems to be to run cmake as root (e.g. with sudo), but you should not have to do that.