ZephyrProject Zephyr up to 4.4.1 SDIO I/O subsys/sd/sdio.c sdio_io_rw_extended_helper infinite loop

Summaryinfo

A vulnerability categorized as critical has been discovered in ZephyrProject Zephyr up to 4.4.1. This affects the function sdio_io_rw_extended_helper of the file subsys/sd/sdio.c of the component SDIO IO. The manipulation results in infinite loop. This vulnerability is cataloged as CVE-2026-15923. The attack must be initiated from a local position. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in ZephyrProject Zephyr up to 4.4.1. Affected is the function sdio_io_rw_extended_helper of the file subsys/sd/sdio.c of the component SDIO IO. The manipulation with an unknown input leads to a infinite loop vulnerability. CWE is classifying the issue as CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. This is going to have an impact on availability. CVE summarizes:

The Zephyr SDIO subsystem function sdio_io_rw_extended_helper() in subsys/sd/sdio.c finishes transfers with a byte-I/O loop that uses size = MIN(remaining, func->cis.max_blk_size) as the per-iteration step. The value func->cis.max_blk_size is decoded directly from the SDIO card's CIS FUNCE tuple in sdio_decode_cis() and is not validated. When a card reports a maximum block size of zero, size is always 0, remaining never decreases, and the loop spins forever. The loop is reached from the public SDIO client API used by drivers, including sdio_read_fifo(), sdio_write_fifo(), and the incrementing register read/write helpers, each of which enters the loop while holding the per-card mutex func->card->lock. A card advertising max_blk_size == 0 therefore hangs the calling thread permanently on its first non-block-aligned transfer and never releases the mutex, denying service to the SDIO peripheral (and any subsystem such as Wi-Fi that depends on it) until the device is reset. The malicious value must come from the SDIO card itself, so the defect is exploitable where a removable SDIO/combo card slot lets an attacker insert a crafted or malfunctioning card (a physical attack vector); on boards with a soldered SDIO peripheral it is not attacker-influenceable. There is no memory-safety, confidentiality, or integrity impact — only a permanent availability loss. The fix returns -EIO when func->cis.max_blk_size is zero, before the loop is entered.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-15923 since 07/16/2026. The exploitability is told to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit.

Upgrading to version 4.4.2 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• ZephyrProject

Name

• Zephyr

Version

• 4.4.0
• 4.4.1

CPE 2.3info

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CPE 2.2info

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