Tenda F456 Router Buffer Overflow Vulnerability (CVE-2026-7101)

A critical buffer overflow vulnerability, identified as CVE-2026-7101, has been discovered in Tenda F456 router version 1.0.0.5. The vulnerability resides in the fromWrlclientSet function within the /goform/WrlclientSet file, which is part of the router’s httpd component. Successful exploitation allows remote attackers to execute arbitrary code on the device. Publicly available exploit code exists, increasing the risk of widespread exploitation. This vulnerability poses a significant threat to home and small business networks using the affected Tenda router model, potentially leading to complete device compromise and unauthorized network access. The vulnerability was published on 2026-04-27 and is tracked by VulDB.

Attack Chain

1. An attacker identifies a vulnerable Tenda F456 router running firmware version 1.0.0.5.
2. The attacker crafts a malicious HTTP request targeting the /goform/WrlclientSet endpoint.
3. The crafted request includes an oversized payload designed to overflow the buffer in the fromWrlclientSet function.
4. The httpd process attempts to process the request without proper bounds checking.
5. The buffer overflow occurs, overwriting adjacent memory regions, including critical program data and execution pointers.
6. The attacker gains control of the program execution flow.
7. The attacker executes arbitrary code on the router, potentially including shell commands or custom malware.
8. The attacker achieves complete control of the router, potentially enabling network reconnaissance, data exfiltration, or further attacks on the local network.

Impact

Successful exploitation of this buffer overflow vulnerability allows a remote attacker to execute arbitrary code on the Tenda F456 router. This can lead to complete device compromise, allowing the attacker to control network traffic, modify router settings, or use the compromised device as a pivot point for further attacks within the network. Given the wide usage of Tenda routers in home and small business environments, a successful widespread exploitation could impact thousands of users.

Recommendation

• Upgrade to a patched firmware version if available from the vendor.
• Implement network segmentation to limit the impact of a compromised router.
• Monitor web server logs for suspicious activity targeting the /goform/WrlclientSet endpoint using the provided Sigma rule.
• Implement an IPS rule to detect and block exploit attempts targeting CVE-2026-7101.