CVE-2026-19823 in W20E
Summary
by MITRE • 08/14/2026
A security flaw has been discovered in Tenda W20E 15.11.0.6(1068_1546_841)_CN_TDC. Impacted is the function formQOSRuleDel of the file /goform/delQos of the component QoS Rule Deletion. Performing a manipulation of the argument qosIndex results in stack-based buffer overflow. Remote exploitation of the attack is possible. The exploit has been released to the public and may be used for attacks.
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Analysis
by VulDB Data Team • 08/14/2026
This vulnerability exists within the Tenda W20E wireless router firmware version 15.11.0.6, specifically in the Quality of Service QoS Rule Deletion functionality. The flaw is located in the formQOSRuleDel function within the /goform/delQos file, which handles the removal of Quality of Service rules from the device configuration. The vulnerability manifests as a stack-based buffer overflow when processing the qosIndex argument parameter, representing a critical security weakness that allows remote attackers to manipulate the device's memory structure through crafted input data. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a severe memory corruption flaw that can lead to arbitrary code execution and system compromise.
The technical exploitation of this vulnerability occurs through remote manipulation of the qosIndex parameter in the QoS Rule Deletion function, where insufficient input validation allows an attacker to provide malicious data that exceeds the allocated buffer space on the stack. When the device processes this oversized input, it overflows into adjacent memory locations, potentially corrupting critical program execution flow and enabling attackers to execute arbitrary code with the privileges of the affected service. The attack vector is fully remote, meaning no physical access or local network presence is required for exploitation, making it particularly dangerous in unsecured network environments.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as successful exploitation can result in complete system compromise and unauthorized access to the router's administrative functions. Attackers could potentially gain persistent access to the device, modify network configurations, intercept traffic, or use the compromised router as a pivot point for attacking other devices within the local network. The public availability of exploit code significantly increases the risk level, as it removes the barrier to entry for malicious actors who may not possess advanced exploitation capabilities. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1059 Command and Scripting Interpreter and T1021 Remote Services, where compromised network devices serve as attack platforms.
Mitigation strategies should prioritize immediate firmware updates from Tenda to address the buffer overflow vulnerability, while network administrators should implement additional security controls such as restricting remote access to administrative interfaces and monitoring for anomalous traffic patterns that may indicate exploitation attempts. The device should be configured with strong authentication mechanisms and regular security audits performed to identify potential compromise indicators. Network segmentation and intrusion detection systems should also be deployed to prevent lateral movement if exploitation occurs, while the affected firmware version should be considered deprecated and replaced with secure alternatives. Organizations should also consider implementing network access control policies that limit which devices can communicate with administrative interfaces, reducing the attack surface for remotely exploitable vulnerabilities like this one.