CVE-2022-40860 is a critical stack overflow vulnerability identified in the Tenda AC15 router firmware version V15.03.05.19. The flaw exists within the function formSetQosBand, specifically at the internal function address FUN_0007dd20, which processes requests sent to the endpoint /goform/SetNetControlList. This vulnerability is classified under CWE-787 (Out-of-bounds Write), indicating that improper handling of input data leads to memory corruption. Exploiting this vulnerability allows an unauthenticated attacker to send a specially crafted HTTP request to the router's web management interface, triggering a stack overflow. Given the CVSS 3.1 base score of 9.8, the vulnerability is highly severe, with network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The impact includes complete compromise of confidentiality, integrity, and availability (C:H/I:H/A:H) of the affected device. Successful exploitation could enable remote code execution, allowing attackers to take full control of the router, intercept or manipulate network traffic, disrupt network services, or pivot into internal networks. Although no public exploits are currently known in the wild, the critical nature and ease of exploitation make this a significant threat to users of the Tenda AC15 router. The lack of an official patch at the time of reporting further exacerbates the risk. This vulnerability highlights the risks associated with embedded device firmware and the importance of secure input validation in network device management interfaces.

For European organizations, the exploitation of CVE-2022-40860 could have severe consequences. The Tenda AC15 router is commonly used in small to medium-sized enterprises and residential environments, which may serve as entry points into corporate networks. Compromise of these routers can lead to interception of sensitive communications, unauthorized access to internal systems, and disruption of business operations. Given the criticality of the vulnerability, attackers could deploy malware, establish persistent backdoors, or conduct man-in-the-middle attacks, threatening data confidentiality and integrity. Additionally, availability could be impacted through denial-of-service conditions caused by exploitation. The risk is particularly pronounced in organizations lacking network segmentation or robust perimeter defenses. Furthermore, the vulnerability could be leveraged in botnet campaigns or as part of broader cyber-espionage operations targeting European entities. The absence of a patch increases exposure time, necessitating immediate mitigations to prevent exploitation.

1. Immediate network-level controls: Block access to the router's management interface (/goform/SetNetControlList endpoint) from untrusted networks, especially the internet, using firewall rules or access control lists. 2. Disable remote management features on the Tenda AC15 router if not strictly necessary, to reduce the attack surface. 3. Monitor network traffic for unusual or malformed HTTP requests targeting the router's web interface, employing intrusion detection/prevention systems with custom signatures for this vulnerability. 4. Segment networks to isolate routers from critical infrastructure and sensitive data environments, limiting lateral movement in case of compromise. 5. Regularly audit and inventory network devices to identify the presence of Tenda AC15 routers and verify firmware versions. 6. Engage with Tenda support channels to obtain official patches or firmware updates addressing this vulnerability as soon as they become available. 7. As a temporary workaround, consider replacing vulnerable devices with alternative hardware from vendors with timely security update practices. 8. Educate IT staff about this vulnerability and encourage prompt application of security advisories related to network infrastructure devices.