CVE-2026-19737 zephyrproject CVE debrief

Who should care

System administrators and developers using the Zephyr operating system, particularly those working with the ESP32 I2S driver, should assess their exposure to this vulnerability. This vulnerability can lead to a system crash, and its exploitation requires user-mode access to the I2S device.

Why it matters

This vulnerability allows a user-mode thread to trigger a kernel-mode crash, potentially leading to a system denial of service. It is particularly relevant for developers and administrators working with the Zephyr operating system and the ESP32 I2S driver, especially in environments where user-mode threads have access to I2S devices.

• Potential system crash due to NULL pointer dereference
• Elevation of privileges from user mode to kernel mode
• Denial of Service (DoS) due to system crash
• Verification of patch application and system hardening required

Technical summary

The `i2s_esp32_trigger_check()` function in the ESP32 I2S driver does not properly validate the requested direction for `I2S_DIR_RX` and `I2S_DIR_TX` branches. This can lead to a NULL pointer dereference when a user-mode thread triggers an unsupported direction. The vulnerability is exploitable on builds with `CONFIG_USERSPACE` enabled, particularly on RISC-V SoCs with `CONFIG_RISCV_PMP`. A user-mode thread with granted I2S device access can trigger a load from address 0 in kernel mode, potentially leading to a system crash. The issue arises from inadequate validation of the requested direction in the `i2s_esp32_trigger_check()` function, particularly for `I2S_DIR_RX` and `I2S_DIR_TX` branches. The device's I2S

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patch referenced in the CVE record
• Restrict access to the I2S device to trusted user-mode threads
• Monitor system logs for potential crashes or errors related to the I2S driver
• Perform a thorough review of the system configuration and user-mode thread access to the I2S device
• Implement additional monitoring and logging to detect potential exploitation attempts
• Verify that the patch has been successfully applied and that the system is no longer vulnerable
• Track and document any exceptions or issues encountered during the remediation process

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description, affected versions, and references to the patch and advisory. However, there is limited information on the exploitation of this vulnerability in the wild.

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.