Edimax EW-7438RPn Stack-Based Buffer Overflow Vulnerability (CVE-2026-9462)

A stack-based buffer overflow vulnerability, identified as CVE-2026-9462, affects Edimax EW-7438RPn version 1.31. The vulnerability resides within the formWpsProxyEnable function of the /goform/formWpsProxyEnable file. By manipulating the submit-url argument, a remote attacker can trigger a buffer overflow, potentially leading to arbitrary code execution. According to the NVD advisory published on May 25, 2026, a public exploit is available, increasing the risk of exploitation. The vendor was notified about this vulnerability, but has not responded. This vulnerability poses a significant threat to devices running the affected firmware version.

Attack Chain

1. Attacker identifies an Edimax EW-7438RPn device running firmware version 1.31.
2. Attacker crafts a malicious HTTP request targeting the /goform/formWpsProxyEnable endpoint.
3. The malicious request includes a submit-url argument with a payload exceeding the buffer size allocated for it within the formWpsProxyEnable function.
4. The formWpsProxyEnable function processes the request without proper bounds checking on the submit-url argument.
5. The oversized submit-url payload overwrites memory on the stack, including the return address.
6. The function attempts to return, but instead jumps to an address controlled by the attacker, allowing for code execution.
7. The attacker executes arbitrary commands on the device.
8. The attacker gains full control of the device, potentially using it for malicious purposes such as botnet participation, data exfiltration, or pivoting to other network resources.

Impact

Successful exploitation of CVE-2026-9462 allows a remote attacker to execute arbitrary code on the affected Edimax EW-7438RPn device. This could lead to complete device compromise, allowing the attacker to modify device settings, intercept network traffic, or use the device as a launchpad for further attacks within the network. Given the availability of a public exploit, the risk of widespread exploitation is elevated.

Recommendation

• Monitor web server logs for requests targeting the /goform/formWpsProxyEnable endpoint with abnormally long submit-url arguments to detect exploitation attempts using the Sigma rule provided.
• Apply network intrusion detection system (IDS) rules to detect and block malicious HTTP requests targeting the vulnerable endpoint.
• Although no patch is available, consider isolating vulnerable Edimax EW-7438RPn devices from critical network segments to limit the potential impact of a successful exploit.