CVE-2026-15892: Missing Release of Memory after Effective Lifetime

The mcumgr SMP settings-management group handlers settingsmgmtread, settingsmgmtwrite, and settingsmgmtdelete in subsys/mgmt/mcumgr/grp/settingsmgmt/src/settingsmgmt.c allocate a keyname buffer and, for read, a data buffer via kmalloc when CONFIGMCUMGRGRPSETTINGSBUFFERTYPEHEAP is enabled, relying...