CVE-2026-28521 is an out-of-bounds read vulnerability identified in the Tuya arduino-TuyaOpen library, specifically in the TuyaIoT component, affecting all versions prior to 1.2.1. The vulnerability arises when the library processes DP (Data Point) event data received from the Tuya cloud service. An attacker who gains control over or hijacks the Tuya cloud infrastructure can send maliciously crafted DP event data to devices running the vulnerable library. This malicious data triggers out-of-bounds memory reads, which can lead to unintended disclosure of sensitive memory contents or cause the device to crash, resulting in a denial-of-service condition. The CVSS 4.0 base score is 7.0 (high severity), reflecting that the attack vector is local (AV:L), requires low attack complexity (AC:L), no privileges (PR:N), no user interaction (UI:N), but impacts confidentiality and availability with high impact (VC:H, VA:H). The vulnerability does not require authentication or user interaction on the device side, but exploitation depends on the attacker’s ability to manipulate the Tuya cloud service, which acts as a trusted intermediary. The affected product, arduino-TuyaOpen, is a widely used open-source library for integrating Tuya IoT capabilities into embedded devices, including smart home appliances, industrial sensors, and other connected devices. The lack of known exploits in the wild suggests limited current exploitation, but the potential impact on confidentiality and availability is significant, especially given the widespread deployment of Tuya-based IoT devices worldwide. The vulnerability highlights the risks associated with cloud-dependent IoT ecosystems, where compromise of the cloud service can cascade to device-level impacts.

The primary impact of CVE-2026-28521 is on the confidentiality and availability of IoT devices using the vulnerable arduino-TuyaOpen library. Successful exploitation can lead to unauthorized disclosure of sensitive memory contents, potentially exposing cryptographic keys, credentials, or other sensitive data stored in device memory. Additionally, the out-of-bounds read can cause device crashes or instability, resulting in denial-of-service conditions that disrupt device functionality. For organizations deploying Tuya-based IoT devices in critical environments such as smart buildings, industrial automation, or healthcare, this could lead to operational disruptions, data leakage, and increased attack surface for further compromise. The dependency on the Tuya cloud service as an attack vector means that a compromise or hijacking of the cloud infrastructure could have widespread cascading effects on all connected devices. This elevates the risk profile for organizations relying heavily on Tuya IoT ecosystems, potentially affecting supply chain security and operational continuity. The vulnerability also underscores the importance of securing cloud services that manage IoT devices, as cloud compromise can translate directly into device-level attacks.

1. Upgrade all affected devices and systems to arduino-TuyaOpen version 1.2.1 or later as soon as the patch becomes available to eliminate the out-of-bounds read vulnerability. 2. Implement strict security controls and monitoring on the Tuya cloud service environment to prevent unauthorized access or hijacking, including multi-factor authentication, anomaly detection, and network segmentation. 3. Employ network-level filtering and validation of DP event data where possible to detect and block malformed or suspicious payloads before they reach devices. 4. Conduct regular firmware integrity checks and runtime memory protection mechanisms on IoT devices to detect abnormal behavior or crashes indicative of exploitation attempts. 5. Establish incident response plans specifically for IoT cloud service compromises, including rapid isolation and remediation procedures. 6. Collaborate with Tuya and device manufacturers to ensure timely vulnerability disclosures and coordinated patch management. 7. For critical deployments, consider additional layers of encryption and authentication between devices and cloud services to reduce trust on the cloud data integrity. 8. Maintain an inventory of all Tuya-based devices in the environment to prioritize patching and monitoring efforts effectively.