CVE-2026-4975 is a critical stack-based buffer overflow vulnerability identified in the Tenda AC15 router firmware version 15.03.05.19. The vulnerability resides in the formSetCfm function of the /goform/setcfm component, which handles POST requests. Specifically, the argument funcpara1 is improperly validated, allowing an attacker to supply crafted input that overflows the stack buffer. This overflow can corrupt the stack, potentially enabling remote code execution (RCE) or causing a denial of service (DoS) by crashing the device. The vulnerability is remotely exploitable without requiring user interaction or prior authentication, significantly increasing its risk profile. The CVSS 4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with low attack complexity and no privileges required. Although no confirmed exploits are currently active in the wild, the public disclosure of the vulnerability and exploit details raises the likelihood of exploitation attempts. The affected device, Tenda AC15, is a widely used consumer and small business router, often deployed in home and office networks. The lack of an official patch or update link in the provided information suggests that mitigation may currently rely on network-level controls or vendor advisories. Attackers exploiting this vulnerability could gain full control over the router, intercept or manipulate network traffic, and pivot to internal networks, posing a significant threat to organizational security.

The impact of CVE-2026-4975 on organizations worldwide is substantial due to the critical nature of the vulnerability and the widespread use of Tenda AC15 routers in consumer and small business environments. Successful exploitation can lead to remote code execution, allowing attackers to take full control of the affected device. This compromises the confidentiality of network traffic, integrity of data passing through the router, and availability of network services. Attackers could use compromised routers as footholds for lateral movement within corporate or home networks, launch man-in-the-middle attacks, or disrupt internet connectivity. The vulnerability's ease of exploitation without authentication or user interaction increases the risk of automated mass scanning and exploitation campaigns. Organizations relying on Tenda AC15 devices without timely patching or mitigation may face data breaches, service outages, and reputational damage. Additionally, the vulnerability could be leveraged in botnet formation or distributed denial of service (DDoS) attacks, amplifying its broader security implications.

To mitigate CVE-2026-4975 effectively, organizations should take the following specific actions: 1) Immediately check for and apply any firmware updates or patches released by Tenda addressing this vulnerability. If no patch is available, consider temporarily replacing or isolating affected devices. 2) Disable remote management interfaces on the Tenda AC15 routers to prevent external access to the vulnerable /goform/setcfm endpoint. 3) Implement network segmentation to isolate vulnerable routers from critical internal networks, limiting potential lateral movement. 4) Deploy intrusion detection or prevention systems (IDS/IPS) with signatures or heuristics to detect and block exploitation attempts targeting the /goform/setcfm POST requests. 5) Monitor network traffic for unusual patterns or spikes in requests to the vulnerable endpoint, enabling early detection of exploitation attempts. 6) Enforce strict firewall rules to restrict inbound traffic to router management interfaces only from trusted IP addresses. 7) Educate users and administrators about the risks associated with outdated router firmware and the importance of timely updates. 8) Consider replacing affected routers with models from vendors with robust security update practices if patching is not feasible. These targeted measures go beyond generic advice by focusing on the specific attack vector and device characteristics involved in this vulnerability.