CVE-2026-19185

What it is

The system-call verifier for i3c_do_ccc() in drivers/i3c/i3c_handlers.c validated the outer struct i3c_ccc_payload, the broadcast ccc.data buffer and the targets.payloads[] array, but did not validate the per-target data buffers those array elements point at. Each struct i3c_ccc_target_payload carries its own data pointer and data_len, and neither was passed through K_SYSCALL_MEMORY() before the payload was handed to z_impl_i3c_do_ccc() and on to the controller driver. The verifier also operated on the caller's live structure rather than a snapshot, so validated fields could be changed by a second user thread between the check and the driver's use — unlike the sibling z_vrfy_i3c_transfer(), which has always copied its message array first. The defect is only present in CONFIG_USERSPACE builds, where drivers/i3c/i3c_handlers.c is compiled. An unprivileged user-mode thread that has been granted access to the I3C controller device object — the ordinary way an application lets a user thread talk to I3C peripherals — can issue a direct CCC whose target payload data pointer names an arbitrary kernel address. Controller drivers dereference that pointer directly (for example drivers/i3c/i3c_mcux.c, drivers/i3c/i3c_cdns.c, drivers/i3c/i3c_stm32.c, drivers/i3c/i3c_npcx.c), using rnw to decide direction. A read CCC therefore causes the kernel-mode driver to write bus-received bytes into an attacker-chosen kernel address for an attacker-chosen length, and a write CCC transmits kernel memory out onto the I3C bus. The result is an out-of-bounds kernel write plus a kernel memory disclosure, i.e. escalation from a user-mode thread to supervisor privilege, defeating the isolation CONFIG_USERSPACE is meant to provide. The fix introduces copy_ccc_and_do(), which snapshots the payload, copies the target array into kernel memory with k_usermode_alloc_from_copy() (bounding num_targets to fewer than 32), validates each per-target buffer with K_SYSCALL_MEMORY() according to rnw, and copies the driver-written num_xfer and err fields back to the caller.

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. 2026-08-06 18:36 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-10-05 09:17 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: 7.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-10-05 09:17 UTC

Last modified

2026-11-04 05:18 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-822

Record status

Awaiting Analysis

Attack profile CVSS 3.1 · 7.8

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

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-2026-19185.md and follow it. Check whether this project is affected by CVE-2026-19185. 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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