CVE-2022-40874 is a high-severity heap overflow vulnerability identified in the Tenda AX1803 router firmware version 1.0.0.1. The flaw exists within the GetParentControlInfo function, which processes HTTP requests. Specifically, a carefully crafted HTTP request can trigger a heap overflow condition, leading to a denial of service (DoS) state. This vulnerability is categorized under CWE-787 (Out-of-bounds Write), indicating that the software writes data outside the boundaries of allocated memory, potentially corrupting memory and causing crashes or unpredictable behavior. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact is limited to availability, with no direct confidentiality or integrity compromise reported. Although no public exploits have been observed in the wild, the high CVSS score of 7.5 reflects the ease of exploitation and the significant impact on device availability. The absence of vendor or product-specific patch information suggests that mitigation may currently rely on network-level controls or firmware updates once available. Given that the Tenda AX1803 is a consumer-grade Wi-Fi 6 router, this vulnerability could affect home and small office environments where this model is deployed. Attackers could leverage this flaw to disrupt network connectivity by causing the router to crash or reboot, resulting in denial of service for all connected clients.

For European organizations, the primary impact of CVE-2022-40874 is the potential disruption of network availability due to router crashes induced by malicious HTTP requests. This can affect business continuity, especially for small and medium enterprises (SMEs) or branch offices relying on Tenda AX1803 routers for internet connectivity. Although the vulnerability does not compromise data confidentiality or integrity directly, the denial of service can interrupt critical communications, remote work, and access to cloud services. In sectors with high dependence on stable internet connections, such as finance, healthcare, and manufacturing, such disruptions could lead to operational delays and financial losses. Additionally, if attackers use this vulnerability as part of a broader attack chain, it could serve as a vector for further exploitation or lateral movement within a network. The lack of authentication and user interaction requirements increases the risk, as attackers can exploit the vulnerability remotely without prior access. However, the absence of known exploits in the wild reduces immediate threat levels but does not eliminate the risk of future exploitation.

To mitigate CVE-2022-40874 effectively, European organizations should first identify any deployment of Tenda AX1803 routers within their network infrastructure. Since no official patches are currently linked, organizations should: 1) Restrict external access to router management interfaces by implementing firewall rules that block unsolicited inbound HTTP requests to the router from untrusted networks. 2) Segment the network to isolate critical systems from consumer-grade routers, limiting the impact of potential DoS attacks. 3) Monitor network traffic for abnormal HTTP request patterns targeting the router, which may indicate exploitation attempts. 4) Engage with Tenda support channels to obtain firmware updates or advisories addressing this vulnerability. 5) Consider replacing vulnerable devices with enterprise-grade routers that receive timely security updates. 6) Employ intrusion detection/prevention systems (IDS/IPS) capable of detecting anomalous HTTP requests or known attack signatures related to heap overflow attempts. 7) Educate IT staff on the risks associated with consumer-grade networking equipment and enforce policies to minimize their use in critical environments.