CVE-2025-52471 is a high-severity integer underflow vulnerability (CWE-191) found in the ESP-NOW protocol implementation within the ESP Wi-Fi component of the Espressif Internet of Things Development Framework (ESP-IDF). The affected versions include 5.4.1, 5.3.3, 5.2.5, and 5.1.6. The root cause is insufficient validation of user-supplied data length in the packet receive function, specifically in the RX callback registered via esp_now_register_recv_cb(). This can cause an integer underflow when the data length parameter is manipulated, leading to out-of-bounds memory access and potentially arbitrary memory write operations. On devices lacking memory protection schemes, this vulnerability could be exploited remotely to achieve code execution, compromising device confidentiality, integrity, and availability. Later patched versions (5.4.2, 5.3.4, 5.2.6, and 5.1.6) include enhanced validation logic to prevent this underflow. For versions prior to 5.4, a workaround involves validating that the data length parameter is positive before processing. However, for versions 5.4 and later, no application-level workaround exists, making upgrading to patched versions critical. The vulnerability has a CVSS 4.0 base score of 7.2, reflecting its high severity with network attack vector, low attack complexity, no user interaction, and partial requirement for attacker privileges. No known exploits are currently reported in the wild. Given the widespread use of ESP-IDF in IoT devices, especially in smart home, industrial, and consumer electronics, this vulnerability poses a significant risk to embedded systems relying on Espressif chips and software stacks.

European organizations deploying IoT devices based on Espressif ESP-IDF, particularly those using the ESP-NOW protocol for device-to-device communication, face a heightened risk of remote compromise. Exploitation could lead to unauthorized control over affected devices, data leakage, or disruption of critical IoT services. This is especially concerning for sectors such as smart manufacturing, energy management, building automation, and smart city infrastructure prevalent in Europe. Compromise of these devices could serve as entry points for lateral movement within enterprise networks or critical infrastructure. The lack of memory protection on many embedded devices exacerbates the risk of remote code execution, potentially allowing attackers to deploy persistent malware or disrupt device functionality. Given the increasing reliance on IoT in European industries and public services, this vulnerability could impact operational continuity, safety systems, and data privacy compliance. Although no active exploits are reported, the vulnerability's ease of exploitation and network accessibility make timely remediation essential to prevent future attacks.

1. Immediate upgrade to patched ESP-IDF versions 5.4.2, 5.3.4, 5.2.6, or later is strongly recommended to leverage built-in validation fixes. 2. For devices running ESP-IDF versions prior to 5.4, implement application-level validation in the RX callback to ensure the data_len parameter is strictly positive before processing to mitigate underflow risks. 3. Conduct an inventory audit of all IoT devices using Espressif chips and ESP-IDF to identify vulnerable firmware versions. 4. Where firmware upgrade is not immediately feasible, isolate vulnerable devices on segmented networks with strict access controls to limit exposure. 5. Monitor network traffic for anomalous ESP-NOW packets that could indicate exploitation attempts. 6. Collaborate with device manufacturers and vendors to ensure timely firmware updates and security patches are deployed. 7. Employ runtime protections such as memory protection units (MPUs) or secure boot features where hardware supports them to reduce impact of memory corruption. 8. Integrate vulnerability scanning and IoT asset management tools to maintain ongoing visibility of device security posture.