A critical vulnerability has been identified in multiple Tenda networking products, allowing a remote attacker to take complete control of affected devices. By sending a specially crafted web request, an attacker can trigger a buffer overflow and execute arbitrary code, posing a severe risk to network security, data confidentiality, and service availability. Due to the public availability of an exploit, this vulnerability is highly likely to be targeted by malicious actors.

This is a stack-based buffer overflow vulnerability in the /bin/httpd web server process running on affected Tenda devices. Specifically, the flaw exists within a function of the R7websSsecurityHandler component, which improperly handles the Cookie header of incoming HTTP requests. A remote, unauthenticated attacker can send a request with an overly long or malformed Cookie value, overflowing the buffer on the stack and overwriting critical program data, which can lead to arbitrary code execution with the privileges of the web server process (typically root).

This vulnerability is rated as critical severity with a CVSS score of 9.8, indicating a high potential for significant business disruption. Successful exploitation could lead to the complete compromise of affected network devices. An attacker could intercept sensitive data passing through the network, pivot to attack other internal systems, disrupt network availability, or incorporate the compromised device into a botnet for use in larger attacks like Distributed Denial of Service (DDoS). This presents a direct threat to data confidentiality, network integrity, and the overall security posture of the organization.

Immediate Action: Update A vulnerability was determined in Tenda Multiple Products to the latest version. The primary remediation is to immediately identify all affected Tenda devices within the environment and apply the latest firmware updates provided by the vendor. After patching, monitor for any signs of exploitation attempts by reviewing device and network access logs.

Proactive Monitoring: Security teams should actively monitor for signs of compromise or exploitation attempts. This includes reviewing web server logs on the devices for unusually long or malformed Cookie headers, monitoring for unexpected device reboots or configuration changes, and scrutinizing network traffic for anomalous outbound connections from the devices to unknown external IP addresses.

Compensating Controls: If patching cannot be performed immediately, organizations should implement compensating controls. Restrict access to the device's web management interface from the internet or any untrusted network. If possible, place the device behind a Web Application Firewall (WAF) or Intrusion Prevention System (IPS) with signatures designed to detect and block buffer overflow attacks in HTTP headers.

Public Exploit Available: true

This vulnerability represents a critical and immediate threat to the organization. Given the 9.8 CVSS score, the remote and unauthenticated nature of the attack, and the public availability of exploit code, this issue must be addressed with the highest priority. We strongly recommend that all affected Tenda devices be identified and patched immediately. If patching is not feasible, the devices should be isolated from the internet and untrusted networks until they can be updated or replaced.