CVE-2026-9263 zephyrproject CVE debrief

Who should care

Defenders responsible for Zephyr-based systems, particularly those using Bluetooth functionality, should assess exposure and prioritize patching affected versions. They should also review and update their inventory of Zephyr-based systems, monitor Bluetooth communications for potential anomalies, and verify and apply patches for affected versions.

Why it matters

CVE-2026-9263 is a medium-severity vulnerability in Zephyr's Bluetooth controller ISO Adaptation Layer, allowing remote information disclosure. Defenders should prioritize patching affected versions and monitoring Bluetooth communications.

• Information disclosure through leaked adjacent memory
• Potential for triggering out-of-bounds reads
• Need for verification and patching of affected Zephyr versions
• Monitoring of Bluetooth communications for anomalies

Technical summary

The Zephyr Bluetooth controller ISO Adaptation Layer (subsys/bluetooth/controller/ll_sw/isoal.c) fails to validate the length field of a framed ISO PDU start segment. This leads to an out-of-bounds read that leaks adjacent memory into host HCI ISO packets, allowing a remote CIS peer or broadcaster to trigger information disclosure. The vulnerability affects Zephyr-based systems using Bluetooth functionality, particularly those with exposed Bluetooth controllers. Defenders should prioritize verifying and applying patches for Zephyr versions 3.3.0 to 4.3.1 and 4.4.0 to 4.4.1, as well as monitoring Bluetooth communications for potential anomalies.

Defensive priority

Defenders should prioritize verifying and applying patches for Zephyr versions 3.3.0 to 4.3.1 and 4.4.0 to 4.4.1, as well as monitoring Bluetooth communications for potential anomalies.

Recommended defensive actions

• Verify and apply patches for Zephyr versions 3.3.0 to 4.3.1 and 4.4.0 to 4.4.1
• Monitor Bluetooth communications for potential anomalies
• Review and update inventory of Zephyr-based systems
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• 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
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description, affected versions, and references to patches and advisories. However, there is limited information on potential exploits or attacks.

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.