Tenda F453 Router Stack-Based Buffer Overflow Vulnerability

CVE-2026-4552 is a critical vulnerability affecting Tenda F453 routers, specifically version 1.0.0.3. The vulnerability resides in the fromVirtualSer function within the /goform/VirtualSer component of the router's firmware. A remote attacker can exploit this flaw by sending a specially crafted request to the router, manipulating the page argument. Due to the lack of proper input validation, the attacker can trigger a stack-based buffer overflow, potentially leading to arbitrary code execution on the device. This vulnerability is particularly concerning as the exploit is publicly disclosed, increasing the likelihood of widespread exploitation. Successful exploitation grants the attacker full control over the compromised router, potentially enabling them to intercept network traffic, modify router settings, or use the device as a pivot point for further attacks within the network.

Attack Chain

1. The attacker identifies a vulnerable Tenda F453 router running firmware version 1.0.0.3.
2. The attacker crafts a malicious HTTP request targeting the /goform/VirtualSer endpoint.
3. The crafted request includes the page argument with a payload exceeding the buffer size allocated for it in the fromVirtualSer function.
4. The router processes the HTTP request without proper input validation, leading to a buffer overflow on the stack.
5. The overflow overwrites critical data on the stack, including the return address.
6. When the fromVirtualSer function returns, control is transferred to the attacker-controlled address.
7. The attacker executes arbitrary code on the router, gaining control of the device.
8. The attacker can then modify router settings, intercept network traffic, or use the compromised router as a foothold for further attacks.

Impact

Successful exploitation of CVE-2026-4552 allows a remote attacker to gain complete control over the Tenda F453 router. This can lead to a variety of malicious activities, including eavesdropping on network traffic, modifying DNS settings to redirect users to phishing sites, or using the router as a botnet node for distributed denial-of-service (DDoS) attacks. Given the widespread use of Tenda routers in home and small business networks, a large number of devices are potentially vulnerable. The potential damage includes data theft, financial loss, and disruption of network services.

Recommendation

• Deploy the Sigma rule Tenda_F453_Buffer_Overflow_Attempt to detect suspicious requests to the /goform/VirtualSer endpoint with unusually long page parameters.
• Monitor web server logs for HTTP requests with a cs-uri-query containing page= followed by a long string of characters, as detected by the Tenda_F453_Buffer_Overflow_Attempt rule.
• If possible, implement web application firewall (WAF) rules to block requests with overly long page parameters to prevent exploitation of CVE-2026-4552.
• Consider network segmentation to limit the impact of a compromised router on other devices and systems on the network.