CVE-2025-11386 is a stack-based buffer overflow vulnerability identified in the Tenda AC15 router firmware version 15.03.05.18. The vulnerability resides in an unspecified function within the POST parameter handler for the /goform/SetDDNSCfg endpoint, which processes the ddnsEn argument. Improper handling of this argument allows an attacker to overflow the stack buffer remotely, without requiring authentication or user interaction. This type of vulnerability can lead to arbitrary code execution on the device or cause it to crash, resulting in denial of service. The vulnerability has a CVSS 4.0 base score of 8.7, indicating high severity, with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Although no exploits have been observed in the wild, proof-of-concept exploits have been publicly disclosed, increasing the risk of exploitation. The affected product, Tenda AC15, is a popular consumer-grade router used globally, often in home and small office environments. The lack of available patches at the time of disclosure increases the urgency for mitigation. The vulnerability’s exploitation could allow attackers to gain control over the router, intercept or manipulate network traffic, or disrupt network connectivity.

The impact of CVE-2025-11386 is significant for organizations and individuals using the Tenda AC15 router. Successful exploitation can lead to full compromise of the router, allowing attackers to execute arbitrary code with system-level privileges. This can result in interception or manipulation of network traffic, unauthorized access to internal networks, and disruption of internet connectivity. For businesses, especially small offices relying on these routers, this could lead to data breaches, loss of confidentiality, and operational downtime. The vulnerability also poses risks to home users, potentially exposing personal data or enabling the router to be used as part of a botnet. Given the router’s role as a network gateway, compromise can serve as a foothold for lateral movement within connected networks. The public availability of exploit code increases the likelihood of attacks, especially by opportunistic threat actors. The absence of patches or official fixes at disclosure time exacerbates the threat, making mitigation critical to prevent exploitation.

To mitigate CVE-2025-11386, organizations and users should first check for any firmware updates from Tenda addressing this vulnerability and apply them immediately once available. In the absence of patches, network administrators should restrict access to the router’s management interface, especially blocking remote access to the /goform/SetDDNSCfg endpoint via firewall rules or access control lists. Disabling DDNS functionality temporarily can reduce attack surface if feasible. Monitoring network traffic for unusual POST requests targeting the vulnerable endpoint can help detect exploitation attempts. Employ network segmentation to isolate critical systems from devices using the affected router. Additionally, consider replacing the affected router with a device from a vendor with a strong security track record if patching is not possible. Regularly audit router configurations and change default credentials to prevent unauthorized access. Finally, maintain updated intrusion detection/prevention systems that can recognize exploit patterns related to this vulnerability.