{"cve":{"cve_id":"CVE-2026-19569","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.0012,"epss_percentile":0.01699,"epss_as_of":"2026-10-15","description":"dynamic_object_create() in kernel/userspace/userspace.c computed the backing allocation for a dynamically allocated kernel object as obj_size_get(otype) + size, and for thread stack elements as STACK_ELEMENT_DATA_SIZE(size) (a round-up plus fixed overhead), without checking either expression for unsigned wrap-around. A size close to SIZE_MAX makes the computed total wrap to a very small value, so the heap chunk handed out is a few bytes while the object descriptor is still tagged with the full requested type and registered in the kernel object table.\n\nThe size argument reaches that arithmetic directly from user mode. k_object_alloc_size() is declared __syscall in include/zephyr/sys/kobject.h, its verifier z_vrfy_k_object_alloc_size() in kernel/userspace/userspace_handler.c is a bare pass-through, and z_object_alloc() only range-checks otype — nothing bounds size. The stack-element branch is additionally reachable through the k_thread_stack_alloc() syscall via kernel/dynamic.c. Because subsequent kernel-object validation checks only the object's type and initialization state, the undersized handle passes K_SYSCALL_OBJ_INIT()/K_SYSCALL_OBJ_NEVER_INIT(), and the matching init syscall (for example k_mutex_init(), k_sem_init(), or k_thread_create()) then writes a complete object over the truncated allocation.\n\nAn unprivileged user-mode thread can therefore trigger a supervisor-mode out-of-bounds write into the kernel resource-pool heap, of a size and content it substantially controls, corrupting sys_heap chunk metadata and adjacent kernel objects. Under CONFIG_GEN_PRIV_STACKS the thread-stack branch additionally stores an attacker-influenced wild pointer as a user thread's privileged stack base. The practical result is escape from the CONFIG_USERSPACE sandbox — kernel-level code execution or at minimum kernel memory corruption and system compromise.\n\nExploitation requires CONFIG_USERSPACE together with CONFIG_DYNAMIC_OBJECTS (also selected by CONFIG_DYNAMIC_THREAD under userspace), and a calling thread with an assigned resource pool. The fix rejects both overflowing computations and frees the partially built descriptor.","published_at":"2026-10-09T07:16:45.305000Z","last_modified_at":"2026-10-09T18:17:07.760000Z","cvss_v3_score":8.8,"cvss_v3_vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cvss_v3_severity":"HIGH","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-190"],"nvd_references":["https://github.com/zephyrproject-rtos/zephyr/commit/85c1c4c21945d9b8fcef03216f1ccb2b27794e3d","https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-fg8c-9fhq-q7hv"],"vuln_status":"Awaiting Analysis","trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-10-09T08:37:29.212723Z","updated_at":"2026-10-12T01:08:57.935686Z"},"effective_severity":"HIGH","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"L","value_label":"Local"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"L","value_label":"Low"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"C","value_label":"Changed"},{"metric":"C","name":"Confidentiality","value":"H","value_label":"High"},{"metric":"I","name":"Integrity","value":"H","value_label":"High"},{"metric":"A","name":"Availability","value":"H","value_label":"High"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"zephyrproject","vendor_name":"zephyrproject","product_slug":"zephyr","product_name":"zephyr","version_start":"3.5.0","version_start_inclusive":true,"version_end":"4.4.2","version_end_inclusive":true,"cpe23_uri":"cve5:zephyrproject:zephyr:3.5.0:4.4.2"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/85c1c4c21945d9b8fcef03216f1ccb2b27794e3d","source_type":"PATCH","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-fg8c-9fhq-q7hv","source_type":"VENDOR_ADVISORY","tags":["advisory"]}],"timeline":[{"type":"published","at":"2026-10-09T07:16:45.305000Z","label":"CVE published","source":null}]}