# CVE-2026-9817: Totolink X2000R stack-based buffer overflow in boa formUploadFile

Source: https://junglewise.ai/threats/cve-2026-9817-a-stack-based-buffer-overflow-vulnerability-exists-in-the-boa  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-9817 · Severity: critical · CVSS 9.1 · Published 2026-10-20

The Totolink X2000R is a home router that manages network configuration through a web interface. A stack-based buffer overflow vulnerability in the file upload functionality allows an authenticated attacker to execute arbitrary code on the router by sending a specially crafted HTTP request with an oversized filename. This could give an attacker complete control over the router and access to all connected devices and network traffic.

Technologies: [TOTOLINK X2000r](https://junglewise.ai/threats/technologies/x2000r). Vendors: [TOTOLINK](https://junglewise.ai/threats/vendors/totolink).

## Quick answers

**Is CVE-2026-9817 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-9817 being exploited in the wild.

**How severe is CVE-2026-9817?** Critical severity, with a CVSS score of 9.1, published 20 October 2026.

**Which products and versions are affected?** TOTOLINK X2000r TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327.

**Is there a fix for CVE-2026-9817?** 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-2026-9817 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-9817?** Check whether you run TOTOLINK X2000r 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 (CWE-121) exists in the formUploadFile() function of the boa web server binary when processing multipart form data uploads. The vulnerability occurs at line [4] where a filename extracted from the HTTP request is copied into a fixed-size stack buffer (0xc8 bytes) without length validation using sprintf(). An authenticated attacker can exploit this via a crafted HTTP POST request to the /boafrm/formUploadFile endpoint with a malicious filename in the multipart data, resulting in stack corruption and arbitrary code execution.

## Affected products

- Totolink X2000R TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327

## Timeline

- 2026-10-20: disclosed
- 2026-10-20: advisory

## References

- [https://talosintelligence.com/vulnerability_reports/TALOS-2026-2429](https://talosintelligence.com/vulnerability_reports/TALOS-2026-2429)

## Related threats

- [TOTOLINK X2000R stack-based buffer overflow in formTR069Config](https://junglewise.ai/threats/cve-2026-9869-a-stack-based-buffer-overflow-vulnerability-exists-in-the-boa)
- [Totolink X2000R arbitrary file write in boa formUploadFile](https://junglewise.ai/threats/cve-2026-9827-a-arbitrary-file-write-vulnerability-exists-in-the-boa)
- [Totolink X2000R OS command injection in formWizard](https://junglewise.ai/threats/cve-2026-9814-an-os-command-injection-vulnerability-exists-in-the-boa-formwizard)
- [TOTOLINK X2000R stack-based buffer overflow in boa formFilter](https://junglewise.ai/threats/cve-2026-9660-multiple-exploitable-stack-based-buffer-overflow-vulnerabilities)
- [TOTOLINK X2000R stack-based buffer overflow in boa formFilter](https://junglewise.ai/threats/cve-2026-9659-multiple-exploitable-stack-based-buffer-overflow-vulnerabilities)