Attack Chain

1. The attacker identifies a Tenda CX12L router running firmware version 16.03.53.12.
2. The attacker sends a crafted HTTP POST request to /goform/RouteStatic.
3. The request includes a page argument with a string exceeding the buffer size allocated to the fromRouteStatic function.
4. The oversized page argument overwrites adjacent memory on the stack, including the return address.
5. When the fromRouteStatic function returns, it attempts to jump to the overwritten return address controlled by the attacker.
6. The attacker’s payload, injected via the overflowed buffer, is executed with the privileges of the httpd process.
7. The attacker gains remote code execution on the router.
8. The attacker can then use the compromised router as a foothold for further attacks, such as network reconnaissance, lateral movement, or data exfiltration.

Impact

Successful exploitation of CVE-2026-5686 allows a remote attacker to execute arbitrary code on the affected Tenda CX12L router. This could lead to a complete compromise of the device, enabling attackers to modify router settings, intercept network traffic, or use the router as a proxy for malicious activities. Given the widespread use of Tenda routers in home and small business networks, this vulnerability could have a significant impact, potentially affecting thousands of users. A successful attack could lead to data breaches, service disruptions, and further compromise of connected devices within the network.

Recommendation

• Apply available patches or firmware updates provided by Tenda to address CVE-2026-5686.
• Monitor web server logs for suspicious POST requests to /goform/RouteStatic with unusually long page parameters, using the provided Sigma rule.
• Implement network intrusion detection systems (IDS) to detect and block exploit attempts targeting this vulnerability.
• Restrict access to the router’s administrative interface to trusted networks or IP addresses to limit the attack surface.
• Regularly review router configurations and security settings to ensure they align with best practices.

Attack Chain

Since no specific exploit details are provided in the source, the following attack chain describes the general steps involved in exploiting a stack-based buffer overflow when processing a frame request.

1. An attacker crafts a malicious frame request.
2. The frame request is sent to the vulnerable Qualcomm component.
3. The component’s software processes the frame request.
4. A stack-based buffer overflow occurs due to insufficient bounds checking when handling the request.
5. The attacker overwrites adjacent memory on the stack, including return addresses.
6. Upon function return, execution is redirected to attacker-controlled code.
7. The attacker executes arbitrary code, potentially gaining control of the device.

Impact

Successful exploitation of CVE-2025-47391 can lead to arbitrary code execution, potentially allowing an attacker to gain complete control over the affected device. Given the widespread use of Qualcomm components in mobile devices and other embedded systems, the impact could be significant, affecting a large number of users. The memory corruption vulnerability could allow for data theft, device compromise, and denial of service.

Recommendation

• Monitor network traffic for suspicious frame requests targeting Qualcomm-based devices, and deploy the network connection rule below to detect unusual outbound activity after potential exploitation.
• Analyze process memory for unusual code execution patterns, and implement the process creation rule to detect unexpected processes being launched.
• Review and apply the security updates provided in the Qualcomm Security Bulletin for April 2026 to patch CVE-2025-47391.
• Monitor for registry modifications indicative of persistence, using the registry_set rule below to detect unusual registry changes.

Attack Chain

1. The attacker crafts a malicious V7 file designed to exploit the buffer overflow in VS6ComFile!CV7BaseMap::WriteV7DataToRom.
2. The user opens the malicious V7 file using a vulnerable version of V-SFT (6.2.10.0 or prior).
3. V-SFT attempts to parse the V7 file, specifically calling the CV7BaseMap::WriteV7DataToRom function.
4. During the WriteV7DataToRom function execution, the crafted V7 file provides input that exceeds the buffer size allocated on the stack.
5. The excessive input overwrites adjacent memory locations on the stack, including the return address.
6. Upon completion of the WriteV7DataToRom function, control is transferred to the overwritten return address.
7. The attacker redirects code execution to a location containing malicious code injected into the process memory.
8. The injected code executes with the privileges of the V-SFT application, potentially leading to complete system compromise.

Impact

Successful exploitation of CVE-2026-32925 allows an attacker to execute arbitrary code on systems running vulnerable versions of V-SFT (6.2.10.0 and prior). This could result in complete system compromise, data theft, or denial of service. The exact number of potential victims is unknown, but the severity is high due to the potential for arbitrary code execution.

Recommendation

• Apply the patch or upgrade to a non-vulnerable version of V-SFT as provided by the vendor (Fujielectric). Refer to the vendor advisory (https://felib.fujielectric.co.jp/en/M10010/M20060/document_detail/5d9dd71d-9494-41a4-aa5c-8e6b8b21066b?region=en-glb).
• Monitor process creation events for V-SFT spawning unusual child processes, which might indicate successful code execution. Utilize the Sigma rule “Detect Suspicious V-SFT Child Processes” to identify such behavior.
• Implement file integrity monitoring for the V-SFT executable and related libraries to detect unauthorized modifications.