NewIntroducing ISO360 — our all-in-one ISO compliance platform
R4IM — Room for Improvement
All advisories
CVE-2026-10667HIGH · CVSS 7.8

CVE-2026-10667

What's the vulnerability?

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.

R4IM analyst take

Business impact & how R4IM helps

This advisory is on our active-exploitation watchlist. Attackers are using it for initial access, privilege escalation or lateral movement in real-world intrusions. R4IM's offensive security and SOC teams already have detections, exploit replicas and remediation playbooks for this issue.

Validate your exposure

Targeted vulnerability assessment to confirm which of your assets are actually exploitable — not just theoretically affected.

Prove it with a pentest

Our pentesters chain this CVE into realistic attack paths so you see business impact, not just a scan finding.

Web app security testing

If the affected product is internet-facing, our AppSec team will harden it against this and related OWASP-class issues.

24/7 SOC & detection

Continuous monitoring with custom detections for this CVE deployed across your endpoints, identity and cloud.

Talk to a security engineer →

Recommended remediation

  1. Inventory all assets running the affected vendor and product, including shadow IT and third-party hosted instances.
  2. Apply the vendor patch or mitigation referenced in the advisories below. Where no patch exists, isolate the asset or restrict network exposure.
  3. Hunt for indicators of prior compromise — exploitation of this class of bug often predates public disclosure.
  4. Deploy detections for the exploit primitives (network signature, EDR rule, WAF rule) and re-test after remediation.

Need help executing these steps? Our team typically completes validation and remediation within a single patch cycle. Request remediation support →

Vendor & research references