# CVE-2026-42020: Totolink X2000R stack-based buffer overflow in formIpv6Setup pppoe

Source: https://junglewise.ai/threats/cve-2026-42020-multiple-stack-based-buffer-overflow-vulnerabilities-exist-in-the  
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-2026-42020 · Severity: critical · CVSS 9.1 · Published 2026-10-20

The Totolink X2000R is a home router that manages internet connectivity and network security. A vulnerability in its web interface allows an authenticated attacker to send a specially crafted request that overwrites the router's memory, leading to complete device compromise and arbitrary code execution. An attacker with router access could take full control of the device, intercept traffic, or use it as a pivot point for attacking the home network.

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

## Quick answers

**Is CVE-2026-42020 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42020 being exploited in the wild.

**How severe is CVE-2026-42020?** Critical severity, with a CVSS score of 9.1, published 20 October 2026.

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

**Is there a fix for CVE-2026-42020?** 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-2026-42020 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-42020?** 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 overflows exist in the formIpv6Setup pppoe functionality (pppoe_dns1 and pppoe_dns2 parameters) of the boa web server, where user input is copied to the stack without bounds checking. An authenticated attacker can trigger arbitrary code execution via crafted HTTP POST requests. Talos verified the vulnerability in version TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327.

## Affected products

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

## Timeline

- 2026-10-20: disclosed

## References

- [https://talosintelligence.com/vulnerability_reports/TALOS-2026-2394](https://talosintelligence.com/vulnerability_reports/TALOS-2026-2394)

## 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 stack-based buffer overflow in boa formUploadFile](https://junglewise.ai/threats/cve-2026-9817-a-stack-based-buffer-overflow-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)