CVE-2025-9813 is a high-severity buffer overflow vulnerability discovered in the Tenda CH22 router, specifically affecting version 1.0.0.1. The vulnerability resides in the function formSetSambaConf within the /goform/SetSambaConf endpoint. An attacker can remotely exploit this flaw by manipulating the samba_userNameSda argument, which leads to a buffer overflow condition. This type of vulnerability typically allows an attacker to overwrite memory adjacent to the buffer, potentially enabling arbitrary code execution, denial of service, or system compromise. The vulnerability is remotely exploitable without user interaction and requires low attack complexity, with no privileges or authentication needed. The CVSS 4.0 score of 8.7 reflects the critical nature of the vulnerability, emphasizing high impact on confidentiality, integrity, and availability. Although no known exploits are currently observed in the wild, a public exploit is available, increasing the risk of active exploitation. The vulnerability does not require any user interaction and can be triggered over the network, making it a significant threat to devices exposed to untrusted networks. The lack of available patches at the time of publication further exacerbates the risk for affected users. Given the nature of the vulnerability in a network device that manages Samba configurations, successful exploitation could allow attackers to gain control over the device, intercept or manipulate network traffic, or pivot into internal networks.

For European organizations, the impact of CVE-2025-9813 could be substantial, especially for those relying on Tenda CH22 routers in their network infrastructure. Compromise of these routers could lead to unauthorized access to internal networks, interception of sensitive data, disruption of network services, and potential lateral movement by attackers. Organizations in sectors such as finance, healthcare, government, and critical infrastructure could face data breaches, operational downtime, and regulatory penalties under GDPR if personal data confidentiality or integrity is compromised. The remote exploitability and absence of required authentication increase the risk of widespread attacks, particularly in environments where these routers are deployed with default or weak configurations. Additionally, the public availability of exploits lowers the barrier for attackers, including less skilled threat actors, to leverage this vulnerability. The lack of patches means organizations must rely on network-level mitigations and monitoring until official fixes are released. Overall, this vulnerability poses a high risk to the security posture of European enterprises and service providers using affected devices.

1. Immediate network segmentation: Isolate Tenda CH22 devices from critical network segments and restrict access to the /goform/SetSambaConf endpoint using firewall rules or access control lists (ACLs) to limit exposure. 2. Disable Samba services or related features on the router if not required, reducing the attack surface. 3. Monitor network traffic for unusual requests targeting the /goform/SetSambaConf endpoint or anomalous samba_userNameSda parameter usage. 4. Implement intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics to detect exploitation attempts against this vulnerability. 5. Regularly audit router configurations and firmware versions to identify and inventory affected devices. 6. Engage with Tenda support channels to obtain patches or firmware updates as soon as they become available and plan for timely deployment. 7. Employ network-level anomaly detection to identify potential exploitation attempts and respond promptly. 8. Educate network administrators about the vulnerability and ensure strict credential management to prevent unauthorized access to router management interfaces. 9. Consider replacing affected devices with alternative hardware if patches are delayed or unavailable, especially in high-risk environments.