CVE-2026-15923 zephyrproject CVE debrief

Who should care

Defenders responsible for SDIO-enabled systems, particularly those using Zephyr, should assess exposure and verify SDIO card compatibility. This includes operators, platform administrators, vulnerability management teams, and security teams who need to ensure the security and availability of their systems. They should review the vulnerability details and take necessary actions to prevent potential disruptions.

Why it matters

CVE-2026-15923 is a medium-severity vulnerability in the Zephyr SDIO subsystem that can cause a permanent denial of service when a malicious SDIO card is inserted. Defenders responsible for SDIO-enabled systems, particularly those using Zephyr, should assess exposure and verify SDIO card compatibility to prevent potential disruptions.

• Denial of service to SDIO peripheral and dependent subsystems
• Permanent availability loss requiring device reset
• Potential disruption to Wi-Fi and other dependent subsystems

Technical summary

The Zephyr SDIO subsystem has a vulnerability in the sdio_io_rw_extended_helper() function, which can cause a permanent availability loss when a malicious SDIO card is inserted. The vulnerability occurs when the card reports a maximum block size of zero, causing a loop to spin forever and hang the calling thread. This affects SDIO-enabled systems, particularly those using Zephyr, and may disrupt dependent subsystems like Wi-Fi. There is no memory-safety, confidentiality, or integrity impact — only a permanent availability loss.

Defensive priority

Defenders should prioritize verifying SDIO card compatibility and assessing exposure in SDIO-enabled systems.

Recommended defensive actions

• Verify SDIO card compatibility with Zephyr SDIO subsystem
• Assess exposure in SDIO-enabled systems
• Monitor for SDIO card insertions or modifications
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions and retest remediated assets
• Plan vendor-supported updates or mitigations

Evidence notes

The CVE record and source references provide details on the vulnerability in the Zephyr SDIO subsystem. The NVD entry is currently Awaiting Analysis. Evidence is limited to public CVE and NVD information. Defenders should verify SDIO card compatibility and assess exposure in SDIO-enabled systems. The vulnerability requires physical access to the SDIO card slot to exploit.

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.