{"id":"CVE-2026-10667","summary":"SMP use-after-free in Zephyr `CONFIG_USERSPACE` dynamic kernel-object tracking, reachable from unprivileged user threads","details":"Zephyr's dynamic kernel-object tracking (kernel/userspace/userspace.c, formerly kernel/userspace.c) maintains a doubly-linked list (obj_list) of dynamically allocated kernel objects. Iteration over this list in k_object_wordlist_foreach() was performed under lists_lock using the SAFE iterator (which caches the next node), but list removal and freeing of nodes was performed under different, disjoint spinlocks: objfree_lock in k_object_free() and obj_lock in unref_check(). On an SMP system, while one CPU iterated obj_list under lists_lock, another CPU could unlink and k_free() the dyn_obj node that the iterator had cached as its next pointer, causing the iterator to dereference freed kernel memory (use-after-free / dangling list traversal). All of the racing operations are reachable from unprivileged user-mode threads via system calls: k_object_alloc/k_object_alloc_size and k_object_release drive removals through unref_check() (under obj_lock), while k_thread_abort and thread creation drive the iteration through k_thread_perms_all_clear()/k_thread_perms_inherit() (under lists_lock). A deprivileged user thread on a CONFIG_SMP + CONFIG_USERSPACE build can therefore corrupt the kernel's object-tracking structures across the userspace security boundary, yielding kernel memory corruption (potential privilege escalation) or a kernel crash (denial of service). The fix removes objfree_lock and serializes every obj_list modification under lists_lock, including holding it across find+remove in k_object_free() and around unref_check() in k_thread_perms_clear(). Affects CONFIG_SMP+CONFIG_USERSPACE+CONFIG_DYNAMIC_OBJECTS configurations; the defect dates to the 2019 spinlockification (commit 8a3d57b6cc6, first released in v1.14.0) and shipped through v4.4.0.","aliases":["GHSA-9x5j-h3rh-x579"],"modified":"2026-07-18T03:45:56.211460992Z","published":"2026-07-12T16:16:50.693Z","database_specific":{"cwe_ids":["CWE-416"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10667.json","unresolved_ranges":[{"extracted_events":[{"introduced":"1.14.0"},{"fixed":"4.5.0"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"zephyr"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10667.json"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-9x5j-h3rh-x579"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-10667"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/fdc42fa256b8c2a7b27790f032d5385f8058c4a9"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"0"},{"fixed":"684c9e8f32e4373a21098559f748f06915f950c9"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"v4.4.0"}],"source":"DESCRIPTION"}}],"versions":["v4.4.0-rc3","v4.4.0-rc2","v4.4.0-rc1","v4.3.0","v4.3.0-rc3","v4.3.0-rc2","v4.3.0-rc1","v4.2.0","v4.2.0-rc3","v4.2.0-rc2","v4.2.0-rc1","v4.1.0","v4.1.0-rc3","v4.1.0-rc2","v4.1.0-rc1","v4.0.0","v4.0.0-rc3","v4.0.0-rc2","v4.0.0-rc1","v3.7.0","v3.7.0-rc3","v3.7.0-rc2","v3.7.0-rc1","v3.6.0","v3.6.0-rc3","v3.6.0-rc2","v3.6.0-rc1","zephyr-v3.5.0","v3.5.0","v3.5.0-rc3","v3.5.0-rc2","v3.5.0-rc1","zephyr-v3.4.0","v3.4.0","v3.4.0-rc3","v3.4.0-rc2","v3.4.0-rc1","zephyr-v3.3.0","v3.3.0","v3.3.0-rc3","v3.3.0-rc2","v3.3.0-rc1","zephyr-v3.2.0","v3.2.0","v3.2.0-rc3","v3.2.0-rc2","v3.2.0-rc1","zephyr-v3.1.0","v3.1.0","v3.1.0-rc3","v3.1.0-rc2","v3.1.0-rc1","zephyr-v3.0.0","v3.0.0","v3.0.0-rc3","v3.0.0-rc2","v3.0.0-rc1","v2.7.99","v2.7.0-rc3","v2.7.0-rc2","v2.7.0-rc1","zephyr-v2.6.0","v2.6.0","v2.6.0-rc3","v2.6.0-rc2","v2.6.0-rc1","zephyr-v2.5.0","v2.5.0","v2.5.0-rc4","v2.5.0-rc3","v2.5.0-rc2","v2.5.0-rc1","zephyr-v2.4.0","v2.4.0","v2.4.0-rc3","v2.4.0-rc2","v2.4.0-rc1","zephyr-v2.3.0","v2.3.0","v2.3.0-rc2","v2.3.0-rc1","zephyr-v2.1.0","v2.1.0","zephyr-v2.2.0","v2.2.0","v2.2.0-rc3","v2.2.0-rc2","v2.2.0-rc1","v2.1.0-rc3","v2.1.0-rc2","v2.1.0-rc1","zephyr-v2.0.0","v2.0.0","v2.0.0-rc3","v2.0.0-rc2","v2.0.0-rc1","zephyr-v1.14.0","v1.14.0","v1.14.0-rc3","v1.14.0-rc2","v1.14.0-rc1","zephyr-v1.13.0","v1.13.0","v1.13.0-rc3","v1.13.0-rc2","v1.13.0-rc1","zephyr-v1.12.0","v1.12.0","v1.12.0-rc3","v1.12.0-rc2","v1.12.0-rc1","zephyr-v1.11.0","v1.11.0","v1.11.0-rc3","v1.11.0-rc2","v1.11.0-rc1","zephyr-v1.10.0","v1.10.0","v1.10.0-rc3","v1.10.0-rc2","v1.10.0-rc1","zephyr-v1.9.0","v1.9.0","v1.9.0-rc4","v1.9.0-rc3","v1.9.0-rc2","v1.9.0-rc1","v1.8.99","zephyr-v1.5.0","v1.5.0","v1.7.99","v1.6.99","v1.5.0-rc4","v1.5.0-rc3","v1.5.0-rc2","v1.5.0-rc1","v1.5.0-rc0","zephyr-v1.4.0","v1.4.0","v1.4.0-rc3","v1.4.0-rc2","v1.4.0-rc1","zephyr-v1.3.0","v1.3.0","v1.3.0-rc2","v1.3.0-rc1","zephyr-v1.2.0","v1.2.0","v1.2.0-rc2","v1.2.0-rc1","zephyr-v1.1.0","v1.1.0","v1.1.0-rc1","zephyr-v1.0.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-10667.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}