CVE-2025-5619 is a critical stack-based buffer overflow vulnerability identified in the Tenda CH22 router firmware version 1.0.0.1. The flaw exists in the function formaddUserName within the /goform/addUserName endpoint. Specifically, the vulnerability arises from improper handling of the Password argument, which allows an attacker to overflow the stack buffer. This type of vulnerability can lead to arbitrary code execution, potentially allowing an attacker to take full control of the affected device remotely without requiring user interaction or prior authentication. The vulnerability is remotely exploitable over the network, increasing its risk profile. Although no public exploit is currently known to be actively used in the wild, the exploit code has been publicly disclosed, raising the likelihood of exploitation attempts. The CVSS v4.0 score of 8.7 (high severity) reflects the vulnerability’s ease of exploitation (network attack vector, low complexity, no privileges or user interaction required) and its significant impact on confidentiality, integrity, and availability, all rated as high. The vulnerability does not require any special privileges or user interaction, making it particularly dangerous for exposed devices. Since the vulnerability affects a specific router model and firmware version, the scope is limited to Tenda CH22 devices running version 1.0.0.1. However, given the critical nature of the flaw and the widespread use of Tenda routers in various markets, the risk remains substantial for affected deployments.

For European organizations, this vulnerability poses a significant risk, especially for those using Tenda CH22 routers in their network infrastructure. Successful exploitation could lead to full compromise of the router, enabling attackers to intercept, modify, or disrupt network traffic, launch further attacks within the internal network, or establish persistent backdoors. This could result in data breaches, loss of network availability, and compromise of sensitive information. Small and medium enterprises (SMEs) and home office environments that rely on consumer-grade routers like the Tenda CH22 are particularly vulnerable due to potentially less rigorous network segmentation and security monitoring. Critical infrastructure operators and organizations handling sensitive data could face operational disruptions and regulatory consequences if their networks are compromised. The public disclosure of the exploit increases the urgency for mitigation to prevent opportunistic attacks. Additionally, the lack of an official patch at the time of disclosure means organizations must rely on interim protective measures to reduce exposure.

1. Immediate network segmentation: Isolate Tenda CH22 devices from critical network segments to limit potential lateral movement if compromised. 2. Disable remote management interfaces on the router, especially the /goform/addUserName endpoint, if possible, to reduce the attack surface. 3. Monitor network traffic for unusual activity originating from or targeting Tenda CH22 devices, including unexpected outbound connections or anomalous HTTP requests to the vulnerable endpoint. 4. Implement strict firewall rules to restrict access to router management interfaces to trusted internal IP addresses only. 5. Regularly audit and inventory network devices to identify all Tenda CH22 routers running the vulnerable firmware version. 6. Engage with Tenda support channels to obtain official patches or firmware updates addressing this vulnerability as soon as they become available. 7. Consider replacing vulnerable devices with more secure alternatives if patches are delayed or unavailable. 8. Educate IT staff about the vulnerability and ensure incident response plans include steps for potential exploitation scenarios involving network infrastructure devices.