# CVE-2026-5686: Tenda CX12L stack buffer overflow in /goform/RouteStatic

Source: https://junglewise.ai/threats/cve-2026-5686-tenda-cx12l-stack-buffer-overflow-in-goform-routestatic  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-06. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-5686 · Severity: high · CVSS 8.8 · Published 2026-04-06

A security vulnerability has been identified in the Tenda CX12L router, a device used to provide wireless internet connectivity. An attacker can exploit this flaw to crash the router's management interface or potentially take full control of the device. This could lead to unauthorized monitoring of network traffic or service outages for connected users.

Technologies: [Tenda Cx12l](https://junglewise.ai/threats/technologies/cx12l), [Tenda CX12L Router](https://junglewise.ai/threats/technologies/cx12l-router), [Tenda Cx12l Firmware](https://junglewise.ai/threats/technologies/cx12l-firmware). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2026-5686 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5686 being exploited in the wild.

**How severe is CVE-2026-5686?** High severity, with a CVSS score of 8.8, published 6 April 2026.

**Which products and versions are affected?** Tenda CX12L Router 16.03.53.12.

**Is there a fix for CVE-2026-5686?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-5686 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5686?** Check whether you run Tenda Cx12l, Tenda CX12L Router or Tenda Cx12l Firmware at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stack-based buffer overflow vulnerability exists in the Tenda CX12L router (firmware version 16.03.53.12) within the 'fromRouteStatic' function of the '/goform/RouteStatic' endpoint. The root cause is the unsafe use of the 'sprintf' function, which processes the user-controlled 'page' parameter into a fixed-size 256-byte buffer without proper bounds checking. An attacker can trigger this overflow by sending a POST request with an oversized 'page' argument. Successful exploitation can lead to memory corruption, denial of service (DoS) by crashing the web server process, or arbitrary code execution by overwriting the return address on the stack. A public proof-of-concept (PoC) has been released.

## Affected products

- Tenda CX12L Router 16.03.53.12

## Timeline

- 2026-03-30: disclosed: Initial disclosure on GitHub by researcher
- 2026-04-06: advisory: NVD/VulDB publication date

## References

- [https://github.com/cve-a/lvdan/issues/4](https://github.com/cve-a/lvdan/issues/4)
- [https://vuldb.com/submit/792783](https://vuldb.com/submit/792783)
- [https://vuldb.com/vuln/355513](https://vuldb.com/vuln/355513)
- [https://vuldb.com/vuln/355513/cti](https://vuldb.com/vuln/355513/cti)
- [https://www.tenda.com.cn/](https://www.tenda.com.cn/)

## Related threats

- [Tenda CX12L buffer overflow in setSchedWifi](https://junglewise.ai/threats/cve-2026-11504-tenda-cx12l-buffer-overflow-in-setschedwifi)
- [Tenda CX12L stack overflow in Wi-Fi Configuration Endpoint](https://junglewise.ai/threats/cve-2026-11503-tenda-cx12l-stack-overflow-in-wi-fi-configuration-endpoint)
- [Tenda CX12L stack overflow in formSetPPTPServer](https://junglewise.ai/threats/cve-2026-8138-tenda-cx12l-stack-overflow-in-formsetpptpserver)
- [Tenda CX12L stack overflow in /goform/NatStaticSetting](https://junglewise.ai/threats/cve-2026-5687-tenda-cx12l-stack-overflow-in-goform-natstaticsetting)
- [Tenda CX12L stack buffer overflow in fromAddressNat](https://junglewise.ai/threats/cve-2026-5685-tenda-cx12l-stack-buffer-overflow-in-fromaddressnat)