# CVE-2026-11523: Tenda W20E stack-based buffer overflow in formPortalAuth

Source: https://junglewise.ai/threats/cve-2026-11523-tenda-w20e-stack-based-buffer-overflow-in-formportalauth  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-08. Updated: 2026-06-08  
License: CC BY 4.0 with a link back

CVE-2026-11523 · Severity: high · CVSS 8.8 · Published 2026-06-08

A security vulnerability has been identified in the Tenda W20E enterprise router, a device used to manage business network traffic. An attacker can exploit this flaw to crash the router or potentially take full control of the device with administrative privileges. This could lead to unauthorized access to the internal network, interception of data, or a complete disruption of internet services for the organization.

Technologies: [Tenda W20E](https://junglewise.ai/threats/technologies/w20e). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2026-11523 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-11523 being exploited in the wild.

**How severe is CVE-2026-11523?** High severity, with a CVSS score of 8.8, published 8 June 2026.

**Which products and versions are affected?** Tenda W20E 15.11.0.6.

**Is there a fix for CVE-2026-11523?** 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-2026-11523 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2026-11523?** Check whether you run Tenda W20E 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 exists in the 'formPortalAuth' function within the '/goform/PortalAuth' endpoint of the Tenda W20E (version 15.11.0.6) web management interface. The vulnerability is caused by the unsafe use of the 'strcpy' function when processing the 'gotoUrl' parameter, which is copied into a fixed-size 256-byte stack buffer without length validation. A remote attacker with low privileges can provide an overly long string to overwrite the saved Link Register (LR), leading to a service crash or arbitrary code execution with root privileges. A public exploit has been disclosed.

## Affected products

- Tenda W20E 15.11.0.6

## Timeline

- 2026-06-08: disclosed: Vulnerability published via VulDB and NVD

## References

- [https://github.com/Robots10/IoT_vlu/blob/main/reports/Tenda/formPortalAuth/formPortalAuth.md](https://github.com/Robots10/IoT_vlu/blob/main/reports/Tenda/formPortalAuth/formPortalAuth.md)
- [https://vuldb.com/cve/CVE-2026-11523](https://vuldb.com/cve/CVE-2026-11523)
- [https://vuldb.com/submit/836471](https://vuldb.com/submit/836471)
- [https://vuldb.com/vuln/369143](https://vuldb.com/vuln/369143)
- [https://vuldb.com/vuln/369143/cti](https://vuldb.com/vuln/369143/cti)
- [https://www.tenda.com.cn/](https://www.tenda.com.cn/)

## Related threats

- [Tenda W20E stack buffer overflow in formDelWebAuthWhiteUser](https://junglewise.ai/threats/cve-2026-90689-tenda-w20e-stack-buffer-overflow-in-formdelwebauthwhiteuser)
- [Tenda W20E stack buffer overflow in formIPMacBindAdd](https://junglewise.ai/threats/cve-2026-90688-tenda-w20e-stack-buffer-overflow-in-formipmacbindadd)
- [Tenda W20E buffer overflow in formAddWebAuthUser](https://junglewise.ai/threats/cve-2026-36823-tenda-w20e-buffer-overflow-in-formaddwebauthuser)
- [Tenda W20E buffer overflow in formDelStaState](https://junglewise.ai/threats/cve-2026-36822-tenda-w20e-buffer-overflow-in-formdelstastate)
- [Tenda W20E buffer overflow in formCropAndSetWewifiPic](https://junglewise.ai/threats/cve-2026-36821-tenda-w20e-buffer-overflow-in-formcropandsetwewifipic)