CVE-2026-24111 is a buffer overflow vulnerability identified in the Tenda W20E router firmware version V4.0br_V15.11.0.6. The vulnerability stems from improper handling of the 'userInfo' parameter passed into the addAuthUser function, which internally uses the C standard library function sscanf without validating the size of the input. This lack of bounds checking allows an attacker to craft a specially formatted 'userInfo' string that overflows the buffer allocated for storing user information. Buffer overflows can lead to arbitrary code execution, memory corruption, or denial of service conditions. Since the vulnerability is in the router's firmware, exploitation could allow attackers to gain control over the device, manipulate network traffic, or pivot into internal networks. The vulnerability does not require authentication, implying that attackers with network access to the router's management interface or exposed services could exploit it remotely. No CVSS score has been assigned yet, and no patches or mitigations have been officially released. The vulnerability was reserved in January 2026 and published in March 2026, indicating it is a recent discovery. Tenda W20E routers are popular in consumer and small business environments, especially in Asia, South America, and parts of Eastern Europe, increasing the potential attack surface. The absence of known exploits in the wild suggests the vulnerability is not yet actively exploited, but the risk remains high due to the ease of exploitation and potential impact.

The impact of CVE-2026-24111 is significant for organizations and individuals using the affected Tenda W20E routers. Successful exploitation could lead to remote code execution, allowing attackers to take full control of the device. This control could enable attackers to intercept, modify, or redirect network traffic, compromising confidentiality and integrity of data. Additionally, attackers could disrupt network availability by causing device crashes or reboots. For organizations, this could mean exposure of sensitive internal communications, unauthorized network access, and potential lateral movement within corporate networks. Home users could face privacy breaches and unauthorized use of their internet connections. The vulnerability's ease of exploitation without authentication increases the risk, especially if the router's management interface is exposed to untrusted networks or the internet. The lack of patches means the vulnerability remains unmitigated, increasing the window of opportunity for attackers. Overall, the threat could lead to severe operational disruptions and data breaches.

To mitigate CVE-2026-24111, affected users and organizations should immediately restrict access to the Tenda W20E router's management interfaces by implementing network segmentation and firewall rules that limit access to trusted IP addresses only. Disable remote management features if not required, especially those accessible from the internet. Monitor network traffic for unusual activity that could indicate exploitation attempts. Since no official patches are currently available, users should regularly check Tenda's official channels for firmware updates addressing this vulnerability and apply them promptly once released. Consider replacing vulnerable devices with models from vendors with a strong security track record if immediate patching is not feasible. Employ network intrusion detection systems (NIDS) capable of identifying buffer overflow attack patterns targeting router management protocols. Additionally, educate users about the risks of exposing router management interfaces and enforce strong administrative passwords to reduce the risk of unauthorized access.