CVE-2026-10681: Concurrent Execution using Shared Resource with Improper Synchronization

In Zephyr's userspace dynamic-objects subsystem, threadidxalloc in kernel/userspace/userspace.c allocated a new thread permission index from the global threadidxmap bitmap without holding listslock. On SMP systems, two user-mode threads invoking the kobjectallocKOBJTHREAD syscall concurrently can...