CVE-2025-4007 is a critical stack-based buffer overflow vulnerability identified in the Tenda W12 router and i24 firmware versions 3.0.0.4(2887) and 3.0.0.5(3644). The flaw exists in the httpd component, specifically within the cgidhcpsCfgSet function located in the /goform/modules directory. This function processes a JSON argument, which, when manipulated maliciously, triggers a stack-based buffer overflow. This type of vulnerability allows an attacker to overwrite memory on the stack, potentially leading to arbitrary code execution, denial of service, or system compromise. The vulnerability is remotely exploitable without requiring user interaction or prior authentication, increasing its risk profile. The CVSS 4.0 base score is 8.7 (high severity), reflecting the ease of remote exploitation (attack vector: network), low attack complexity, no privileges required, and no user interaction needed. The impact on confidentiality, integrity, and availability is rated as high, indicating that successful exploitation could lead to full system compromise. Although no public exploits are currently known to be in the wild, the exploit details have been publicly disclosed, which raises the risk of imminent exploitation attempts. The vulnerability affects specific firmware versions, indicating that devices running these versions are at risk until patched or mitigated.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Tenda W12 routers in their network infrastructure. Successful exploitation could allow attackers to gain unauthorized remote control over affected devices, leading to potential data breaches, network disruption, or pivoting to other internal systems. This is particularly critical for enterprises, small and medium businesses, and public sector entities that may use these routers for internet connectivity or internal network segmentation. The compromise of such devices could result in loss of confidentiality of sensitive data, integrity violations through unauthorized configuration changes, and availability issues due to device crashes or reboots. Additionally, since the vulnerability requires no authentication or user interaction, automated scanning and exploitation campaigns could rapidly affect unpatched devices across Europe, amplifying the threat. The public disclosure of the exploit increases the urgency for mitigation to prevent widespread attacks.

1. Immediate firmware upgrade: Organizations should verify the firmware version of their Tenda W12 and i24 devices and upgrade to a version that addresses this vulnerability as soon as a patch is released by the vendor. 2. Network segmentation: Isolate vulnerable devices from critical network segments to limit potential lateral movement if exploitation occurs. 3. Access control: Restrict remote management access to the affected devices by limiting access to trusted IP addresses and disabling remote HTTP management interfaces if not required. 4. Intrusion detection: Deploy network-based intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploitation attempts targeting the /goform/modules endpoint or unusual JSON payloads. 5. Monitoring and logging: Enable detailed logging on routers and monitor for anomalous activities, such as unexpected configuration changes or traffic patterns indicative of exploitation attempts. 6. Vendor engagement: Engage with Tenda support channels to obtain official patches or workarounds and confirm the timeline for remediation. 7. Temporary mitigations: If patches are unavailable, consider disabling or restricting the vulnerable httpd service or applying firewall rules to block suspicious traffic targeting the vulnerable endpoint. These steps go beyond generic advice by focusing on device-specific controls and proactive monitoring tailored to this vulnerability.