The vulnerability CVE-2026-24115 affects the Tenda W20E router firmware version 4.0br_V15.11.0.6 and is classified as a buffer overflow (CWE-120). Specifically, the issue stems from the failure to validate the sizes of two parameters, 'gstup' and 'gstdwn', before concatenating them into a buffer named 'gstruleQos'. This improper validation can lead to a stack-based buffer overflow, allowing an attacker to overwrite memory beyond the intended buffer boundaries. The vulnerability is remotely exploitable over the network without requiring any authentication or user interaction, making it highly accessible to attackers. Successful exploitation could enable arbitrary code execution, potentially granting attackers full control over the affected device. The CVSS v3.1 base score is 9.8, reflecting the critical nature of this flaw with high impact on confidentiality, integrity, and availability. No patches or official fixes have been released yet, and no exploits have been observed in the wild as of the publication date. The vulnerability was reserved in January 2026 and published in March 2026. Given the widespread use of Tenda routers in consumer and small business environments, this vulnerability poses a significant risk to network security and device stability.

The impact of CVE-2026-24115 is severe due to the potential for remote, unauthenticated attackers to execute arbitrary code on vulnerable Tenda W20E routers. This could lead to complete compromise of the device, allowing attackers to intercept, modify, or disrupt network traffic, pivot to internal networks, or deploy persistent malware. Confidentiality is at risk as attackers could capture sensitive data passing through the router. Integrity is compromised by the potential to alter device configurations or injected malicious payloads. Availability could be disrupted through denial-of-service conditions caused by exploitation attempts or malicious control of the device. Organizations relying on these routers for critical network infrastructure or internet access could face significant operational disruptions, data breaches, and increased attack surface. The lack of patches increases the window of exposure, making proactive mitigation essential.

1. Immediately restrict access to the router's management interface by disabling remote administration features if enabled. 2. Implement network-level firewall rules to block unauthorized inbound traffic to the router's management ports (e.g., HTTP/HTTPS, Telnet, SSH). 3. Monitor network traffic for unusual patterns or attempts to exploit buffer overflow conditions targeting the router. 4. Segment the network to isolate vulnerable devices from critical infrastructure and sensitive data. 5. Regularly check for firmware updates from Tenda and apply patches as soon as they become available. 6. Consider replacing affected devices with models from vendors with a strong security track record if patches are delayed. 7. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploitation attempts targeting this vulnerability. 8. Educate network administrators about the risks and signs of exploitation to enable rapid response.