# CVE-2026-42026: Totolink X2000R stack-based buffer overflow in IPv6 DHCP DNS

Source: https://junglewise.ai/threats/cve-2026-42026-multiple-exploitable-stack-based-buffer-overflow-vulnerabilities  
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-2026-42026 · Severity: critical · CVSS 9.1 · Published 2026-10-20

The Totolink X2000R is a budget home router with web-based administration. Multiple stack-based buffer overflow vulnerabilities in the IPv6 DHCP DNS configuration functionality allow an authenticated attacker to send specially crafted HTTP requests and achieve arbitrary code execution on the router. This gives an attacker complete control over the device, enabling data theft, network intrusion, or ransomware deployment.

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

## Quick answers

**Is CVE-2026-42026 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42026 being exploited in the wild.

**How severe is CVE-2026-42026?** 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-2026-42026?** 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-2026-42026 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-42026?** 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

Stack-based buffer overflow vulnerabilities exist in the formIpv6Setup function's handling of dhcp_dns1 and dhcp_dns2 HTTP POST parameters. The vulnerable code uses strcpy() without length checks to copy user-supplied input directly to stack buffers. An authenticated attacker can overflow these buffers via HTTP POST to overwrite the stack and achieve arbitrary code execution; no user interaction is required beyond the initial authentication.

## Affected products

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

## Timeline

- 2026-10-20: disclosed

## References

- [https://talosintelligence.com/vulnerability_reports/TALOS-2026-2396](https://talosintelligence.com/vulnerability_reports/TALOS-2026-2396)

## Related threats

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- [Totolink X2000R arbitrary file write in boa formUploadFile](https://junglewise.ai/threats/cve-2026-9827-a-arbitrary-file-write-vulnerability-exists-in-the-boa)
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- [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)