Zephyrproject Zephyr up to 4.3.1/4.4.x RTIO Syscall Verifier rtio_syscalls.c z_vrfy_rtio_sqe_cancel pointer privileges management

Summaryinfo

A vulnerability classified as very critical was found in Zephyrproject Zephyr up to 4.3.1/4.4.x. Affected is the function z_vrfy_rtio_sqe_cancel of the file subsys/rtio/rtio_syscalls.c of the component RTIO Syscall Verifier. Executing a manipulation of the argument pointer can lead to privileges management. This vulnerability is registered as CVE-2026-16511. The attack needs to be launched locally. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Zephyrproject Zephyr up to 4.3.1/4.4.x. It has been declared as very critical. This vulnerability affects the function z_vrfy_rtio_sqe_cancel of the file subsys/rtio/rtio_syscalls.c of the component RTIO Syscall Verifier. The manipulation of the argument pointer with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Two RTIO syscall verifiers, in subsys/rtio/rtio_syscalls.c (subsys/rtio/rtio_handlers.c before v4.3.0), did not validate user-supplied pointers before the kernel wrote through them. z_vrfy_rtio_sqe_cancel() performed no validation at all. It passed the caller's struct rtio_sqe pointer straight to z_impl_rtio_sqe_cancel(), which converts it with CONTAINER_OF to a struct rtio_iodev_sqe, ORs RTIO_SQE_CANCELED (BIT(3)) into its 16-bit flags field in supervisor mode, then loads its next pointer and repeats until that pointer is NULL. The syscall takes no RTIO context argument, so it needs no object grant: any user-mode thread on a CONFIG_USERSPACE build can set that bit in a 16-bit word at an address of its choosing in kernel memory, and the kernel continues the write along whatever pointer chain it finds at the corresponding offset. Setting chosen bits in kernel data structures, such as object permission or thread state fields, can be used to escalate privilege from user mode. z_vrfy_rtio_sqe_copy_in_get_handles() validated its RTIO context and the input SQE array, but only NULL-checked the handle out-parameter before writing a kernel SQE pointer through it, with no K_SYSCALL_MEMORY_WRITE check. A user thread that holds a granted RTIO context can therefore make the kernel store a pointer value at an arbitrary address. The fixes validate the handle out-parameter as writable, bound the cancel handle to real submission-pool storage, and require permission on the RTIO context that owns the matching pool. Without that last check a bounded handle still let any user thread cancel submissions belonging to other contexts, silently aborting their I/O. Systems built without CONFIG_USERSPACE or without CONFIG_RTIO are unaffected.

The advisory is available at github.com. This vulnerability was named CVE-2026-16511 since 07/21/2026. The exploitation appears to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 11/04/2026). This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Upgrading to version 4.3.2 or 4.5.0 eliminates this vulnerability. Applying the patch b1092a0aa7fbe67118ca4b08d5b4e54b34709a6e is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyrproject

Name

• Zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.3.0
• 4.3.1
• 4.4

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CPE 2.2info

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