CVE-2025-49604 is a heap-based buffer overflow vulnerability identified in Realtek AmebaD devices, specifically affecting the Ameba-AIoT ameba-arduino-d firmware versions prior to 3.1.9 and ameba-rtos-d versions before the commit c2bfd8216a1cbc19ad2ab5f48f372ecea756d67a dated 2025/07/03. The vulnerability resides in the WLAN driver's defragmentation function, which handles fragmented Wi-Fi frames. Due to insufficient validation of the size of these fragmented frames, an attacker can craft malicious Wi-Fi packets that cause a heap overflow when processed by the device. This type of vulnerability can lead to memory corruption, potentially allowing remote code execution, denial of service, or system instability. Since the flaw is in the WLAN driver, exploitation likely requires the attacker to be within wireless range or have network access to the affected device's Wi-Fi interface. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability affects embedded IoT devices using Realtek AmebaD chipsets, which are commonly used in various smart devices, sensors, and industrial IoT applications. The lack of patch links suggests that fixes may be newly released or pending wider distribution. Given the nature of heap overflows in network drivers, this vulnerability poses a significant risk to device integrity and network security if exploited.

For European organizations, the impact of CVE-2025-49604 can be substantial, especially for those deploying IoT devices based on Realtek AmebaD chipsets in critical infrastructure, manufacturing, smart building management, or industrial automation. Exploitation could allow attackers to execute arbitrary code remotely or cause device crashes, leading to operational disruptions. This could compromise confidentiality if attackers gain access to sensitive data processed or transmitted by these devices, integrity if device behavior is altered maliciously, and availability if devices become unresponsive or require replacement. The risk is heightened in environments with large-scale IoT deployments or where devices are exposed to untrusted wireless networks. Additionally, compromised devices could serve as entry points for lateral movement within corporate networks, increasing the overall attack surface. The absence of known exploits currently provides a window for proactive mitigation, but the vulnerability's presence in widely used IoT components necessitates urgent attention to prevent future exploitation.

Organizations should immediately identify and inventory all devices using Realtek AmebaD chipsets, particularly those running Ameba-AIoT ameba-arduino-d versions before 3.1.9 and ameba-rtos-d before the specified commit. Coordinate with device vendors and Realtek for the availability of firmware updates or patches addressing this vulnerability and prioritize their deployment. Where patching is delayed, implement network segmentation to isolate vulnerable IoT devices from critical systems and restrict wireless access to trusted networks only. Employ wireless intrusion detection/prevention systems (WIDS/WIPS) to monitor and block suspicious Wi-Fi frames that could exploit the defragmentation flaw. Additionally, enforce strict access controls and monitor device behavior for anomalies indicative of exploitation attempts. For new deployments, prefer devices with updated firmware or alternative chipsets not affected by this vulnerability. Finally, maintain up-to-date asset management and vulnerability scanning processes to detect and respond to emerging threats related to this issue.