Local privilege escalation via syscall double-fetch
Published Aug 12, 2026 · Updated Aug 12, 2026
TOCTOU in Zephyr RTOS before 4.4.2 allows local users to overwrite kernel heap memory through socket system calls. The z_vrfy_zsock_sendmsg() and z_vrfy_zsock_recvmsg() verifiers size an iovec shadow from one msg_iovlen read, then bound copy loops with later reads of the mutable user header. With CONFIG_USERSPACE and socket syscalls enabled, a cooperating thread can win the race to obtain a privilege-escalation primitive or crash the kernel.
Summary
What happened
TOCTOU in Zephyr RTOS before 4.4.2 allows local users to overwrite kernel heap memory through socket system calls. The z_vrfy_zsock_sendmsg() and z_vrfy_zsock_recvmsg() verifiers size an iovec shadow from one msg_iovlen read, then bound copy loops with later reads of the mutable user header. With CONFIG_USERSPACE and socket syscalls enabled, a cooperating thread can win the race to obtain a privilege-escalation primitive or crash the kernel.
The record
- CVE
- CVE-2026-12234
- Published
- Aug 12, 2026
- Updated
- Aug 12, 2026
- Vendor
- Zephyr Project
- Product
- Zephyr RTOS
- Classifications
- CWE-367, CAPEC-29, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 12, 2026CVE publishedPublication date reported by the CVE source.
- Aug 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.3.0 <4.4.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo