# CVE-2026-42806

## Summary

- **CVE ID:** CVE-2026-42806
- **Severity:** MEDIUM
- **CVSS Score:** 4.3 (CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L)
- **CWE:** CWE-125
- **Published:** Sep 10, 2026
- **Last Modified:** Sep 10, 2026

## Description

An out-of-bounds read vulnerability was discovered in the Bosch BME690 SensorAPI (C-driver) in version v1.0.3 and prior, specifically within the field data parsing logic in read_all_field_data (bme69x.c).

The driver prefetches heater configuration registers into a contiguous 30-byte stack buffer (set_val) mapping IDAC, RES_HEAT, and GAS_WAIT tables.

When parsing sensor field data, the gas_index is extracted using a 4-bit mask (0..15) but lacks boundary verification against the valid range (0..9).

An attacker or a compromised peripheral mimicking a sensor on the I2C/SPI bus could return a payload with a gas index value of 10 or higher.

This causes the driver to perform an out-of-bounds array access (set_val[20 + gas_index]), reading up to 6 bytes past the stack buffer.

The leaked out-of-bounds byte is then written into the public gas_wait field, which may lead to measurement corruption or leak adjacent stack memory when telemetered or logged.

## Affected Products

- Bosch Sensortec — BME690 SensorAPI (C) (1.0.1)

## References

- [CNA](https://psirt.bosch.com/security-advisories/BOSCH-SA-223618.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.15%
- **EPSS Percentile:** 4.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._