PackageKit dnf5 backend: an unprivileged local user can uninstall packages under a simulate flag

Impact

PackageKit skips the polkit authorization check for transactions carrying the SIMULATE dry-run flag. The dnf5 backend's RepoRemove handler guards with (role == REPO_REMOVE || !SIMULATE), which is always true for RepoRemove, so it executes the real transaction regardless. An unprivileged local user who can talk to the PackageKit D-Bus service can therefore perform a genuine removal while nominally simulating. On a GPU node that means someone with a shell can strip packages - a driver package, a runtime dependency - and take the node out of service or leave it in a state that needs rebuilding. Integrity and availability impact only, no disclosure. Affects only systems running PackageKit with the dnf5 backend.

Who can reach it

Any local unprivileged user with access to the PackageKit D-Bus interface on a host using the dnf5 backend. Authentication as a normal user is enough; no polkit prompt is reached.

What to do

Apply your distribution's PackageKit update carrying commit 33be77b (Fedora and RHEL trackers are linked); restarting the packagekitd service picks up the fix, no reboot needed. If a patch is not yet available for your release, the direct mitigation is to remove or disable PackageKit on fleet nodes - unattended GPU hosts rarely need it, since package management runs through configuration management instead.

References

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