CVE-2026-98672 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
iio: adc: stm32-adc: fix possible division by zero in processed channel
In case the conversion has failed or returned zero, processing *val can lead to a division by zero. Need to check for errors, or converted value is zero, before processing the data. In case the converted value is zero, e.g. the Vrefint channel, this should be considered as invalid in all cases.
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified within the Linux kernel's Industrial I/O subsystem specifically affects the STM32 analog-to-digital converter driver. This flaw manifests during the processing of converted data from specific channels where a division by zero operation can occur if certain preconditions are not met. The root cause lies in the handling of conversion results that either indicate an error state or return a value of zero without adequate validation prior to arithmetic operations involving those values as divisors. In embedded systems utilizing STM32 microcontrollers, accurate analog-to-digital conversion is critical for monitoring power supplies, sensor inputs, and other physical parameters. When the driver processes these raw data points, it assumes that the returned integer represents a valid magnitude suitable for further calculation. However, this assumption fails when the hardware reports an error or explicitly returns zero, leading to undefined behavior in the kernel space which can result in system crashes or instability.
From a technical perspective, the flaw is categorized under CWE-369, known as Divide By Zero. This type of vulnerability arises when software performs division by a variable that evaluates to zero without checking for this condition beforehand. In the context of the stm32-adc driver, specific channels such as Vrefint, which measures internal reference voltage, may legitimately return zero under certain conditions or due to hardware quirks. Additionally, if the conversion process fails internally within the ADC peripheral, the returned value might also be zero or an error code interpreted incorrectly by the processing logic. The lack of a guard clause to verify that the divisor is non-zero before executing the division operation allows this mathematical impossibility to propagate through the kernel's data handling pipeline. This represents a classic input validation failure where external hardware states are not sufficiently sanitized before being used in critical arithmetic operations.
The operational impact of this vulnerability can vary depending on how it is triggered and what process context invokes the affected code path. If an unprivileged user or application space component triggers the ADC conversion that results in zero, it could lead to a kernel panic due to division by zero exceptions. This effectively causes a denial of service against the entire system hosting the Linux kernel instance. In more severe scenarios involving privilege escalation vectors, although less likely with this specific arithmetic error, such instability can be exploited to disrupt security controls or crash critical services. The vulnerability primarily affects systems relying on STM32 hardware for analog signal processing and is particularly relevant in industrial automation, IoT devices, and embedded control systems where reliability is paramount. An attacker who can influence the ADC input conditions or trigger repeated conversions might exploit this flaw to cause persistent system unavailability.
To mitigate this risk, developers must implement robust error checking mechanisms within the stm32-adc driver code. The immediate fix involves adding conditional checks before any division operation involving processed channel values. Specifically, the code should verify that the converted value is not zero and that no conversion errors were reported by the hardware interface. If a zero value or an error state is detected, the processing logic should handle it gracefully, either by returning an appropriate error code to user space, logging the anomaly for diagnostic purposes, or treating the reading as invalid data rather than attempting mathematical transformation. This aligns with secure coding practices that emphasize defensive programming and explicit validation of all inputs derived from external sources. Furthermore, integrating this check into the standard processing pipeline ensures consistency across different channel types and prevents regression in future updates to the driver.
From a broader security architecture standpoint, addressing this issue reinforces adherence to principles outlined in the MITRE ATT&CK framework under techniques related to resource exhaustion or service disruption. While not an exploit technique per se, preventing such kernel-level crashes is essential for maintaining system integrity and availability. Security teams managing STM32-based deployments should ensure their kernels are patched with versions containing this fix. Regular auditing of hardware interaction code in embedded Linux environments can help identify similar patterns where raw sensor data is processed without sufficient validation. By enforcing strict checks on divisor values derived from hardware responses, organizations can significantly reduce the attack surface associated with kernel vulnerabilities and enhance the overall resilience of their IoT and industrial infrastructure against potential denial-of-service attacks stemming from simple arithmetic errors.