CVE-2025-13400 is a remote buffer overflow vulnerability found in Tenda CH22 firmware version 1.0.0.1. The flaw exists in the formWrlExtraGet function, which processes the chkHz argument from HTTP requests to the /goform/WrlExtraGet endpoint. Improper handling of this argument allows an attacker to overflow a buffer, potentially overwriting memory and enabling arbitrary code execution or denial of service. The vulnerability requires no authentication or user interaction, making it highly exploitable remotely over the network. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P) indicates network attack vector, low complexity, no privileges or user interaction needed, and high impact on confidentiality, integrity, and availability. Although no confirmed exploitation in the wild has been reported, a public exploit is available, increasing the likelihood of attacks. The affected product, Tenda CH22, is a networking device commonly used in small to medium enterprise and home environments. The vulnerability could allow attackers to gain control over the device, intercept or manipulate network traffic, disrupt services, or pivot into internal networks.

For European organizations, exploitation of CVE-2025-13400 could lead to severe consequences including unauthorized access to network devices, interception or manipulation of sensitive data, disruption of network availability, and potential lateral movement within corporate networks. Organizations relying on Tenda CH22 devices for critical networking functions may experience outages or compromise of internal communications. This is particularly concerning for sectors such as telecommunications, finance, healthcare, and government agencies where network integrity and confidentiality are paramount. The availability of a public exploit increases the risk of opportunistic attacks, including ransomware or espionage campaigns. Additionally, compromised devices could be leveraged as entry points for broader cyberattacks targeting European infrastructure or data assets.

1. Immediately inventory all Tenda CH22 devices running firmware version 1.0.0.1 within the network. 2. Monitor Tenda’s official channels for firmware updates or patches addressing CVE-2025-13400 and apply them promptly once available. 3. Until patches are released, restrict access to the /goform/WrlExtraGet endpoint via firewall rules or network segmentation to limit exposure. 4. Implement intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics to detect anomalous HTTP requests targeting the chkHz parameter. 5. Employ network segmentation to isolate vulnerable devices from critical infrastructure and sensitive data stores. 6. Conduct regular network traffic analysis to identify suspicious activity indicative of exploitation attempts. 7. Educate IT and security teams about this vulnerability and ensure incident response plans include steps for potential exploitation scenarios. 8. Consider replacing or upgrading devices if patching is not feasible within a reasonable timeframe.