CVE-2025-9443 is a high-severity buffer overflow vulnerability identified in the Tenda CH22 router, specifically version 1.0.0.1. The flaw exists in the function formeditUserName within the /goform/editUserName endpoint. This vulnerability arises due to improper handling of the 'new_account' argument, which can be manipulated to overflow the buffer. Buffer overflow vulnerabilities typically allow attackers to overwrite adjacent memory, potentially leading to arbitrary code execution, system crashes, or denial of service. Notably, this vulnerability can be exploited remotely without requiring user interaction or prior authentication, which significantly increases its risk profile. The CVSS 4.0 score of 8.7 reflects its high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges or user interaction needed. Although no known exploits are currently observed in the wild, a public exploit has been published, making exploitation feasible for attackers. The absence of a patch link indicates that a vendor fix may not yet be available, increasing the urgency for mitigation. The vulnerability affects a specific firmware version (1.0.0.1) of the Tenda CH22 router, a device commonly used in small office and home network environments. Given the nature of the vulnerability, successful exploitation could allow attackers to execute arbitrary code on the device, potentially gaining control over the router, intercepting or redirecting network traffic, or launching further attacks within the network.

For European organizations, this vulnerability poses a significant risk, especially for small and medium enterprises (SMEs) and home offices that utilize Tenda CH22 routers. Compromise of these devices could lead to unauthorized network access, interception of sensitive communications, and disruption of business operations. Given the router’s role as a network gateway, attackers could pivot to internal systems, exfiltrate data, or deploy malware. The remote and unauthenticated nature of the exploit increases the likelihood of automated scanning and exploitation campaigns targeting vulnerable devices across Europe. This could result in widespread network outages or breaches, particularly in sectors with less mature cybersecurity postures. Additionally, critical infrastructure entities using these devices could face operational disruptions or espionage risks. The lack of an official patch further exacerbates the threat, potentially leading to prolonged exposure.

Organizations should immediately identify and inventory all Tenda CH22 routers running firmware version 1.0.0.1 within their networks. Until an official patch is released, the following specific mitigations are recommended: 1) Restrict remote access to router management interfaces by implementing firewall rules that limit access to trusted IP addresses only. 2) Disable remote management features if not required. 3) Monitor network traffic for unusual activity targeting the /goform/editUserName endpoint, using intrusion detection systems or custom signatures. 4) Employ network segmentation to isolate vulnerable routers from critical systems. 5) Consider replacing affected devices with models from vendors with timely security updates if patching is not imminent. 6) Stay informed on vendor advisories for patch releases and apply updates promptly. 7) Educate users about the risks of using default or outdated firmware and encourage regular device maintenance. These targeted actions go beyond generic advice by focusing on access control, monitoring, and device lifecycle management specific to this vulnerability.