# CVE-2026-36791: Tenda O3v3 stack overflow in formSetCfm

Source: https://junglewise.ai/threats/cve-2026-36791-tenda-o3v3-stack-overflow-in-formsetcfm  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-36791 · Severity: info · CVSS 7.5 · Published 2026-06-09

A vulnerability exists in the Tenda O3v3 outdoor access point, a device used to provide long-range wireless networking. By sending a specially crafted web request to the device's management interface, an attacker can cause the system to crash or reboot. This results in a denial of service, disrupting internet connectivity and network operations for all connected users.

Technologies: [Tenda O3](https://junglewise.ai/threats/technologies/o3). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2026-36791 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-36791 being exploited in the wild.

**How severe is CVE-2026-36791?** Informational severity, with a CVSS score of 7.5, published 9 June 2026.

**Which products and versions are affected?** Tenda O3 v1.0.0.5.

**Is there a fix for CVE-2026-36791?** 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-2026-36791 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-36791?** Check whether you run Tenda O3 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 'formSetCfm' CGI handler of Tenda O3v3 firmware version v1.0.0.5. The vulnerability is located within the 'save_list_data' function, where a user-controlled parameter (funcpara1) is passed to 'sprintf' without adequate length validation. Specifically, the 'acStack_154' buffer is overflowed when 'sprintf' constructs a string using the tainted input. An unauthenticated remote attacker can trigger this by sending an HTTP request with 'funcname' set to 'save_list_data' and an oversized 'funcpara1' value. While primarily identified as a Denial of Service (DoS) vector, stack overflows in this context may potentially allow for arbitrary code execution.

## Affected products

- Tenda O3v3 v1.0.0.5

## Timeline

- 2026-03-15: other: CVE request submitted to MITRE
- 2026-06-06: disclosed: Public disclosure of vulnerability details
- 2026-06-09: advisory: NVD published CVE-2026-36791

## References

- [https://github.com/xhh0124/SemVulLLM/tree/main/O3/formSetCfm](https://github.com/xhh0124/SemVulLLM/tree/main/O3/formSetCfm)

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