CVE-2026-2186 is a stack-based buffer overflow vulnerability identified in the Tenda RX3 router firmware version 16.03.13.11. The vulnerability resides in the fromSetIpMacBind function, which is accessible via the /goform/SetIpMacBind endpoint. This function improperly handles input arguments, allowing an attacker to craft malicious requests that overflow the stack buffer. The overflow can lead to arbitrary code execution, enabling attackers to gain control over the device remotely without requiring authentication or user interaction. The vulnerability has a CVSS 4.0 base score of 8.7, indicating high severity, with attack vector network (remote), low attack complexity, no privileges required, and no user interaction needed. The impact covers confidentiality, integrity, and availability, as attackers can execute arbitrary commands, potentially disrupting network operations or exfiltrating sensitive data. Although no exploits are currently reported in the wild, the public disclosure of exploit code increases the likelihood of exploitation. The lack of available patches at the time of reporting necessitates immediate mitigation efforts by affected users. The vulnerability is critical for environments relying on Tenda RX3 routers, especially where these devices serve as gateways or manage critical network functions.

For European organizations, exploitation of CVE-2026-2186 could lead to full compromise of affected Tenda RX3 routers, resulting in unauthorized access to internal networks, interception or manipulation of network traffic, and potential lateral movement within corporate environments. This could disrupt business operations, cause data breaches involving sensitive or personal data protected under GDPR, and damage organizational reputation. Critical infrastructure operators and enterprises using Tenda RX3 devices as part of their network infrastructure are particularly vulnerable. The remote, unauthenticated nature of the exploit increases the risk of widespread attacks, especially if attackers leverage disclosed exploit code in automated campaigns. The impact extends beyond individual organizations to potentially affect supply chains and service providers relying on these devices. Given the high CVSS score and the critical role of routers in network security, the threat poses a significant risk to confidentiality, integrity, and availability of European IT environments.

1. Immediately restrict remote access to the router’s management interface by disabling WAN-side administration or limiting access via firewall rules to trusted IP addresses only. 2. Monitor network traffic for unusual or malformed requests targeting /goform/SetIpMacBind and implement intrusion detection/prevention signatures to detect exploitation attempts. 3. If possible, upgrade to a patched firmware version once released by Tenda; in the absence of an official patch, consider temporary device replacement or network segmentation to isolate vulnerable routers. 4. Enforce strict network segmentation to limit the impact of a compromised router and reduce lateral movement opportunities. 5. Conduct regular vulnerability scans and penetration tests focusing on network infrastructure devices to identify and remediate similar issues proactively. 6. Educate IT staff on the risks of exposed router management interfaces and the importance of timely patching and configuration hardening. 7. Engage with Tenda support channels to obtain updates on patch availability and coordinate remediation efforts.