# CVE-2026-36770: Tenda W3 stack overflow in ask_to_reboot function

Source: https://junglewise.ai/threats/cve-2026-36770-tenda-w3-stack-overflow-in-ask-to-reboot-function  
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-2026-36770 · Severity: info · CVSS 7.5 · Published 2026-06-09

A vulnerability exists in the Tenda W3 wireless router, a device used to provide internet connectivity in homes and small offices. An attacker can send a specially crafted web request to the router's management interface to cause the device to crash or reboot. This results in a denial of service, disrupting internet access for all connected users.

Technologies: [Tenda W3 Wireless Router](https://junglewise.ai/threats/technologies/w3-wireless-router). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2026-36770 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-36770 being exploited in the wild.

**How severe is CVE-2026-36770?** Informational severity, with a CVSS score of 7.5, published 9 June 2026.

**Which products and versions are affected?** Tenda W3 Wireless Router US_W3V1.0BR v1.0.0.3(2204).

**Is there a fix for CVE-2026-36770?** 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-2026-36770 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-36770?** Check whether you run Tenda W3 Wireless Router 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 'ask_to_reboot' CGI handler of Tenda W3V1.0BR firmware version v1.0.0.3(2204). The vulnerability is located in the 'ask_to_reboot' function, which is reachable via the wireless configuration handler (FUN_00449844). The handler retrieves the user-controlled HTTP parameter 'GO' using 'websGetVar' and passes it to 'ask_to_reboot'. Inside this function, the input is concatenated into a fixed-size stack buffer using an unbounded 'sprintf' call: 'sprintf(buf, "reboot.asp?page=%s", param_2)'. An attacker can exploit this by sending an excessively long string in the 'GO' parameter, leading to a crash of the 'httpd' process or a device reboot. While primarily a Denial of Service (DoS) risk, arbitrary code execution may be possible depending on the presence of exploit mitigations like stack canaries or ASLR.

## Affected products

- Tenda W3 Wireless Router US_W3V1.0BR v1.0.0.3(2204)

## Timeline

- 2026-03-04: other: CVE request submitted to MITRE
- 2026-06-06: disclosed: Public disclosure
- 2026-06-09: advisory: NVD published date

## References

- [https://github.com/xhh0124/SemVulLLM/tree/main/W3/ask_to_reboot](https://github.com/xhh0124/SemVulLLM/tree/main/W3/ask_to_reboot)

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