CVE-2025-8300 is a high-severity heap-based buffer overflow vulnerability identified in the Realtek rtl81xx SDK Wi-Fi driver, specifically within the function N6CSet_DOT11_CIPHER_DEFAULT_KEY. The vulnerability arises due to improper validation of the length of user-supplied data before copying it into a fixed-length heap buffer. This flaw allows a local attacker, who already has the ability to execute low-privileged code on the target system, to escalate their privileges to SYSTEM level by exploiting the buffer overflow. The vulnerability affects version 1030.38.712.2019 of the rtl81xx SDK. The exploitation does not require user interaction but does require local access with low privileges. The CVSS v3.0 score is 8.8, indicating a high severity with critical impacts on confidentiality, integrity, and availability. The scope is changed (S:C), meaning the vulnerability can affect resources beyond the initially compromised component. Although no known exploits are currently reported in the wild, the vulnerability's nature and impact make it a significant risk, especially in environments where the affected Realtek Wi-Fi drivers are deployed. The vulnerability was assigned by ZDI (Zero Day Initiative) and publicly disclosed on September 2, 2025.

For European organizations, this vulnerability poses a substantial risk, particularly for enterprises and government agencies relying on devices with Realtek rtl81xx SDK Wi-Fi drivers. Successful exploitation allows attackers to elevate privileges from a low-privileged user to SYSTEM, potentially enabling full control over the affected system. This can lead to unauthorized access to sensitive data, disruption of critical services, and deployment of persistent malware or ransomware. Given the widespread use of Realtek network components in laptops, desktops, and embedded systems, the impact could extend across multiple sectors including finance, healthcare, manufacturing, and public administration. The ability to escalate privileges locally also increases the risk from insider threats or attackers who have gained limited initial access through phishing or other means. The vulnerability's exploitation could undermine the confidentiality, integrity, and availability of critical systems, leading to regulatory compliance issues under GDPR and other European data protection laws.

1. Immediate patching is critical; organizations should monitor Realtek and OEM vendor advisories for official patches or updated driver releases addressing this vulnerability. 2. Until patches are available, restrict local access to systems with affected drivers by enforcing strict user account controls and limiting physical and remote access. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious activities indicative of exploitation attempts. 4. Conduct thorough inventory and asset management to identify all devices using the vulnerable Realtek rtl81xx SDK version. 5. Implement network segmentation to isolate critical systems and reduce lateral movement opportunities for attackers. 6. Regularly audit and monitor logs for unusual privilege escalation attempts or anomalous behavior related to Wi-Fi driver operations. 7. Educate users on the risks of executing untrusted code locally, as initial low-privilege code execution is a prerequisite for exploitation. 8. Consider disabling or replacing affected Wi-Fi hardware in high-security environments if immediate patching is not feasible.