CVE-2025-12235 is a buffer overflow vulnerability identified in the Tenda CH22 router firmware version 1.0.0.1. The vulnerability resides in the fromSetIpBind function within the /goform/SetIpBind endpoint, where improper handling of the 'page' argument allows an attacker to overflow a buffer. This flaw can be exploited by an attacker who has access to the local network, as the attack vector requires local network origin but does not require user interaction or elevated privileges beyond local access. The buffer overflow could allow an attacker to execute arbitrary code, potentially leading to full compromise of the router device. The CVSS 4.0 score is 8.6 (high severity), reflecting the low attack complexity, no user interaction, and high impact on confidentiality, integrity, and availability. The vulnerability does not require authentication but does require local network access, which limits remote exploitation but still poses a significant risk in environments where local network access can be gained by malicious insiders or through compromised devices. The exploit code has been publicly disclosed, increasing the likelihood of exploitation attempts. No official patch links are currently provided, indicating that organizations must rely on network-level mitigations until a firmware update is released. The vulnerability affects a specific firmware version, so verifying device versions is critical. Given the role of routers as network gateways, successful exploitation could allow attackers to intercept, modify, or disrupt network traffic, impacting connected systems and data confidentiality and availability.

For European organizations, the impact of this vulnerability can be substantial. Routers like the Tenda CH22 are often deployed in small to medium enterprise environments and home offices, which may have less stringent network security controls. Exploitation could lead to unauthorized access to internal network traffic, enabling data interception, manipulation, or denial of service. This could compromise sensitive business communications, intellectual property, and personal data, potentially violating GDPR requirements. Additionally, compromised routers could be leveraged as footholds for lateral movement within corporate networks or as part of botnets for broader attacks. The requirement for local network access means that attackers could be insiders, contractors, or external actors who have gained initial foothold through phishing or malware. The public availability of exploit code increases the urgency for European organizations to assess and mitigate this risk promptly. Critical infrastructure sectors relying on secure and reliable network connectivity could face operational disruptions, data breaches, or espionage risks.

1. Immediately inventory all Tenda CH22 devices and verify firmware versions to identify affected units running version 1.0.0.1. 2. Apply vendor-provided firmware updates as soon as they become available; monitor Tenda’s official channels for patches. 3. Until patches are available, implement strict network segmentation to isolate vulnerable devices from untrusted local users and devices. 4. Restrict access to the router’s management interfaces to trusted administrators only, using VLANs or firewall rules to limit local network exposure. 5. Monitor network traffic for unusual activity targeting the /goform/SetIpBind endpoint or anomalous requests containing malformed 'page' parameters. 6. Employ intrusion detection/prevention systems (IDS/IPS) capable of detecting buffer overflow attempts or known exploit signatures related to this vulnerability. 7. Educate staff about the risks of local network attacks and enforce strong endpoint security to reduce the risk of initial compromise that could lead to local network access. 8. Consider replacing affected devices with models from vendors with a stronger security track record if timely patching is not feasible.