CVE-2025-13400 is a buffer overflow vulnerability identified in the Tenda CH22 router firmware version 1.0.0.1. The vulnerability resides in the formWrlExtraGet function, which processes requests to the /goform/WrlExtraGet endpoint. Specifically, the chkHz argument is improperly handled, allowing an attacker to craft a malicious request that causes a buffer overflow. This overflow can overwrite memory, potentially enabling remote code execution or causing the device to crash, leading to denial of service. The vulnerability is remotely exploitable without requiring authentication or user interaction, making it highly accessible to attackers scanning for vulnerable devices. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (VC:H, VI:H, VA:H). Although no active exploitation in the wild has been reported, the availability of public exploit code increases the likelihood of future attacks. The lack of an official patch at the time of publication necessitates immediate mitigation efforts by network administrators. This vulnerability affects only version 1.0.0.1 of the Tenda CH22 firmware, so organizations should verify their device versions and apply updates once available. The exploit targets a common router function, which may be exposed to the internet or internal networks, increasing the attack surface. Given the critical role of routers in network infrastructure, successful exploitation could lead to network compromise, data interception, or service disruption.

For European organizations, exploitation of CVE-2025-13400 could result in severe consequences including unauthorized remote code execution on network routers, leading to full compromise of network traffic confidentiality and integrity. Attackers could intercept, modify, or redirect sensitive communications, impacting data privacy compliance such as GDPR. The availability of network services could be disrupted by denial of service conditions caused by the overflow, affecting business continuity. Organizations relying on Tenda CH22 devices in critical infrastructure, small to medium enterprises, or branch offices may face elevated risks due to potentially weaker network segmentation and monitoring. The remote and unauthenticated nature of the exploit increases the attack surface, especially for devices exposed to the internet or poorly secured internal networks. The public availability of exploit code further raises the risk of automated scanning and exploitation campaigns targeting European networks. This could lead to lateral movement within corporate networks or serve as a foothold for broader attacks. The impact is particularly significant for sectors with stringent security requirements such as finance, healthcare, and government institutions. Failure to mitigate this vulnerability promptly could result in regulatory penalties, reputational damage, and operational disruptions.

1. Immediate inventory and identification of all Tenda CH22 devices running firmware version 1.0.0.1 within the network. 2. Monitor Tenda’s official channels for firmware updates addressing CVE-2025-13400 and apply patches as soon as they become available. 3. Until patches are released, implement network-level protections such as firewall rules to block or restrict access to the /goform/WrlExtraGet endpoint, especially from untrusted networks or the internet. 4. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploit attempts targeting this vulnerability. 5. Segment networks to isolate vulnerable devices from critical assets and limit lateral movement in case of compromise. 6. Conduct regular vulnerability scanning and penetration testing to identify exposed Tenda CH22 devices and verify mitigation effectiveness. 7. Educate network administrators about the vulnerability and the importance of monitoring logs for suspicious activity related to the chkHz parameter. 8. Consider replacing outdated or unsupported Tenda CH22 devices with more secure alternatives if patching is delayed or unavailable. 9. Implement strict access controls and network hardening best practices to reduce exposure of management interfaces. 10. Maintain up-to-date backups and incident response plans to quickly recover from potential exploitation.