Linux Kernel CVE-2026-43390

The upstream fix is available via two stable kernel commits: 8d76afe84fa2babf604b3c173730d4d2b067e361 at https://git.kernel.org/stable/c/8d76afe84fa2babf604b3c173730d4d2b067e361 and 0abd81645fc95ec6a9d4e4813000f22c5efc0ff4 at https://git.kernel.org/stable/c/0abd81645fc95ec6a9d4e4813000f22c5efc0ff4. Upgrading to Linux kernel 6.19.9 or 7.0 (or later) resolves the issue per EUVD version data. Red Hat and SUSE users should monitor their vendor security channels for kernel errata incorporating these commits. As a compensating control where immediate patching is not feasible, administrators can constrain namespace listing access by applying mandatory access control (MAC) policies via SELinux or AppArmor to restrict which privileged services are permitted to perform nstree enumeration calls - note that overly broad restrictions may interfere with legitimate service discovery or container runtime operations and should be tested in staging environments before production deployment. Restricting shared-host co-tenancy of mutually untrusted privileged services (i.e., using separate physical or VM hosts) eliminates the cross-service exposure entirely.