CVE-2025-4897 is a critical buffer overflow vulnerability identified in the Tenda A15 router firmware versions 15.13.07.09 and 15.13.07.13. The flaw exists in the HTTP POST request handler component, specifically within the /goform/multimodalAdd endpoint. This vulnerability allows an unauthenticated remote attacker to send specially crafted HTTP POST requests that overflow a buffer, potentially leading to arbitrary code execution or denial of service conditions. The vulnerability does not require user interaction or prior authentication, making it highly exploitable over the network. The CVSS 4.0 score of 8.7 reflects a high severity, with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The impact on confidentiality, integrity, and availability is high, indicating that successful exploitation could allow attackers to fully compromise the device, intercept or manipulate network traffic, or disrupt network connectivity. Although no public exploits are currently known to be in the wild, the disclosure of the vulnerability and its exploitability means that threat actors could develop or deploy exploits imminently. The lack of available patches at the time of disclosure increases the urgency for mitigation. Given the critical role of routers as network gateways, exploitation of this vulnerability could serve as a foothold for lateral movement into enterprise or home networks, data exfiltration, or launching further attacks against connected devices.

For European organizations, the exploitation of CVE-2025-4897 could have significant consequences. Compromised Tenda A15 routers could lead to interception and manipulation of sensitive communications, undermining confidentiality and data integrity. This is particularly concerning for organizations handling personal data under GDPR, as breaches could result in regulatory penalties and reputational damage. Availability impacts could disrupt business operations reliant on stable internet connectivity, especially for small and medium enterprises or remote offices using these routers. The ability to execute arbitrary code remotely without authentication increases the risk of widespread compromise, potentially allowing attackers to establish persistent access, pivot to internal networks, or deploy malware such as ransomware. The vulnerability also poses risks to critical infrastructure sectors that rely on secure and reliable network connectivity. Given the router’s role as a network perimeter device, exploitation could undermine overall network security posture and complicate incident response efforts.

Immediate mitigation steps should include isolating affected Tenda A15 devices from critical network segments and restricting their exposure to untrusted networks. Network administrators should implement strict firewall rules to block inbound HTTP POST requests to the /goform/multimodalAdd endpoint or, if feasible, disable remote management features on these devices. Monitoring network traffic for anomalous POST requests targeting this endpoint can aid in early detection of exploitation attempts. Since no official patches are currently available, organizations should engage with Tenda support channels for firmware updates or advisories. Where possible, replacement of vulnerable devices with models from vendors with robust security update practices should be considered. Additionally, implementing network segmentation and zero-trust principles can limit the impact of a compromised router. Regular backups and incident response plans should be updated to address potential exploitation scenarios. Finally, educating users and administrators about the risks and signs of compromise related to this vulnerability will enhance organizational readiness.