CVE-2026-42806: Out-of-bounds Read (CVSS 4.3)

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.

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CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0015

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

References

Other References

https://psirt.bosch.com/security-advisories/BOSCH-SA-223618.html

Frequently Asked Questions

What is CVE-2026-42806? +

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. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-42806? +

CVE-2026-42806 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0015, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-42806? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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