Out-of-bounds write in the NXP GAU ADC driver due to byte-versus-sample buffer size validation mismatch

Summary

CVE	CVE-2026-19184
State	PUBLISHED
Assigner	zephyr
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-10-05 09:17:12 UTC
Updated	2026-10-06 15:27:05 UTC
Description	The NXP GAU ADC driver (drivers/adc/adc_mcux_gau_adc.c) validated the caller-supplied sequence->buffer_size, which is expressed in bytes, against the number of active channels, which is a sample count. It then stored that byte count directly in data->results_length and used it in mcux_gau_adc_read_samples() as the number of uint16_t slots available. Because each conversion result occupies sizeof(uint16_t) bytes, a buffer that was accepted as "large enough" could be written with up to twice its size in bytes, so every sample past the buffer's midpoint was written out of bounds. adc_read() and adc_read_async() are Zephyr system calls. The syscall verifier in drivers/adc/adc_handlers.c only confirms that the caller owns buffer_size writable bytes (K_SYSCALL_MEMORY_WRITE); deciding whether that size is sufficient for the requested channels and extra_samplings is delegated entirely to the driver. On a build with CONFIG_USERSPACE=y, a user-mode thread that has been granted the ADC device object could therefore submit a deliberately half-sized buffer and cause the driver's work-queue handler — which runs in supervisor mode, outside the caller's MPU restrictions — to write ADC conversion results past the end of that buffer, at an address and for a length of the caller's choosing. The overrun is bounded by the requested sequence: with sequence->options->extra_samplings set, the sampling loop walks the buffer pointer forward across every sampling, so the total overrun can reach the full size of the supplied buffer (kilobytes for a large extra_samplings). The written words are 16-bit ADC conversion results, so the content is only partially attacker-influenced (via the selected analog input, gain and resolution), but the destination and length are fully controlled — sufficient for kernel memory corruption, a crash, or a userspace-to-kernel privilege escalation. Builds without CONFIG_USERSPACE, or on SoCs other than NXP RW61x with the GAU ADC node enabled, are not exposed to the privilege boundary; there the same defect only causes a silent overflow when the application itself passes an undersized buffer. The fix replaces the ad-hoc check with the shared adc_sequence_validate_buffer() helper (validating against num_channels * sizeof(uint16_t)), stores buffer_size / sizeof(uint16_t) in results_length, and corrects the loop bound to a post-decrement so exactly the available number of slots may be written.

Risk And Classification

Primary CVSS: v3.1 8.4 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H

EPSS: 0.001030000 probability, percentile 0.008990000 (date 2026-10-06)

Problem Types: CWE-787 | CWE-787 bounds

Version	Source	Type	Score	Severity	Vector
3.1	[email protected]	Secondary	8.4	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H`
3.1	CNA	CVSS	8.4	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H`

CVSS v3.1 Breakdown

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

High

Availability

High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Zephyrproject	Zephyr	affected 3.7.0 4.5.0 semver	Not specified

References

Reference	Source	Link	Tags
github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j86w-mfgw-...	[email protected]	github.com
github.com/zephyrproject-rtos/zephyr/commit/82b11958065aa85f8644ddc318ff...	[email protected]	github.com
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

There are currently no legacy QID mappings associated with this CVE.