CVE-2025-9089 is a high-severity stack-based buffer overflow vulnerability found in the Tenda AC20 router, specifically in firmware version 16.03.08.12. The flaw exists in the function sub_48E628 within the /goform/SetIpMacBind endpoint. This function improperly handles the argument list, allowing an attacker to overflow the stack buffer remotely without requiring user interaction or prior authentication. Exploiting this vulnerability could enable an attacker to execute arbitrary code on the device, potentially leading to full compromise of the router. The vulnerability is remotely exploitable over the network, increasing its risk profile. Although no known exploits are currently observed in the wild, the public disclosure of the exploit code increases the likelihood of active exploitation attempts. The CVSS 4.0 base score is 8.7, reflecting the vulnerability’s high impact on confidentiality, integrity, and availability, combined with its ease of exploitation and lack of required privileges or user interaction. The absence of patches or vendor-provided mitigations at the time of disclosure further exacerbates the risk. This vulnerability targets a widely deployed consumer and small business networking device, which often serves as a gateway to internal networks, making it a critical security concern.

For European organizations, the exploitation of CVE-2025-9089 could have severe consequences. Compromised Tenda AC20 routers could allow attackers to intercept, manipulate, or redirect network traffic, leading to data breaches or espionage. The integrity and availability of network services could be disrupted, impacting business operations. Small and medium enterprises (SMEs) and home offices relying on Tenda AC20 devices are particularly vulnerable, as these devices often lack advanced security monitoring. Attackers could leverage compromised routers as footholds for lateral movement within corporate networks or as part of botnets for broader attacks. Given the remote exploitability and high severity, this vulnerability poses a significant threat to confidentiality, integrity, and availability of network infrastructure in European organizations.

1. Immediate network segmentation: Isolate Tenda AC20 devices from critical internal networks to limit potential lateral movement if compromised. 2. Disable or restrict access to the /goform/SetIpMacBind endpoint if possible via device configuration or firewall rules to prevent exploitation. 3. Monitor network traffic for unusual patterns or signs of exploitation attempts targeting the router’s management interface. 4. Implement strict access controls on router management interfaces, including IP whitelisting and VPN-only access. 5. Regularly audit and inventory network devices to identify vulnerable Tenda AC20 units and prioritize their replacement or upgrade. 6. Engage with Tenda for firmware updates or patches and apply them promptly once available. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts against this vulnerability. 8. Educate IT staff about this vulnerability and incorporate it into incident response plans to ensure rapid containment if exploitation is detected.