CVE-2026-12234 zephyrproject CVE debrief

Who should care

Users and administrators of the Zephyr operating system, particularly those with unprivileged user threads enabled, should be aware of this vulnerability and take necessary actions to protect their systems. This includes verifying and applying the official patch or update, restricting access to the affected syscalls, and monitoring system logs for suspicious activity. Additionally, operators and security teams should review the vulnerability details and assess their exposure to ensure proper mitigation and remediation efforts are in place. Vulnerability management and security teams should prioritize patching and verifying compensating controls for exposed systems while remediation is scheduled and verified. Those responsible for asset inventory and change management should track exceptions, retest remediated assets, and close the item only after evidence is documented. Those managing monitoring, detection, and logs should check relevant logs for exposed assets that need extra review. Those involved in source tracking should verify the source grounding and evidence limits of the vulnerability information. Those managing rollback and change windows should plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Those managing compensating controls should review compensating controls for exposed systems while remediation is scheduled and verified. Those managing asset inventory should confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. Those managing security teams should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. Those managing security teams should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed and review compensating controls for exposed systems while remediation is scheduled and verified. Those managing security teams should also check relevant monitoring, detection, and logs for exposed assets that need extra review and track exceptions, retest remediated assets, and close the item only after evidence is documented. Those who are

Technical summary

The vulnerability occurs in the userspace syscall verifiers z_vrfy_zsock_sendmsg() and z_vrfy_zsock_recvmsg() in the Zephyr operating system. A double-fetch issue in the handling of the msg_iovlen field allows a cooperating second thread to inflate the field and cause the population loop to write beyond the allocated kernel-heap shadow buffer. This can lead to a local privilege escalation or a kernel-fault denial of service.

Defensive priority

High

Recommended defensive actions

• Verify and apply the official patch or update to the latest version of the Zephyr operating system
• Restrict access to the affected syscalls
• Monitor system logs for suspicious activity
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability is caused by a double-fetch issue in the handling of the msg_iovlen field. A cooperating second thread can inflate the field, causing the population loop to write beyond the allocated kernel-heap shadow buffer. The vulnerability is reachable from an unprivileged user thread when CONFIG_USERSPACE is enabled and the zsock_sendmsg/zsock_recvmsg syscalls are available.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.