CVE-2026-19569

What it is

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. The 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. An 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. Exploitation 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.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-11 19:13 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-10-09 08:16 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-04 05:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 8.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-10-09 08:16 UTC

Last modified

2026-11-04 05:18 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-190 · Integer overflow

Record status

Awaiting Analysis

Attack profile CVSS 3.1 · 8.8

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-19569.md and follow it. Check whether this project is affected by CVE-2026-19569. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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