Is CVE-2026-42021 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-42021 being exploited in the wild.

How severe is CVE-2026-42021?

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-2026-42021?

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-2026-42021 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-42021?

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.

CVE-2026-42021: Totolink X2000R stack-based buffer overflow in network configuration

CVE-2026-42021 · Severity: critical · CVSS 9.1 · Published 2026-10-20

The Totolink X2000R is a budget gigabit router with mesh and IPv6 capabilities commonly deployed in residential networks. Multiple stack-based buffer overflow vulnerabilities in the network configuration interface allow authenticated attackers to execute arbitrary code on the device, potentially compromising the router and all connected networks. Successful exploitation can lead to complete device takeover, unauthorized access to network traffic, and use as a pivot point for further attacks.

Technologies: TOTOLINK X2000r. Vendors: TOTOLINK.

Quick answers

Is CVE-2026-42021 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-42021 being exploited in the wild.
How severe is CVE-2026-42021?: 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-2026-42021?: 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-2026-42021 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-42021?: 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 boa HTTP server's formIpv6Setup handler, specifically in the static_dns1 and static_dns2 parameters, where unsanitized user input is directly copied to stack buffers without bounds checking. The vulnerability requires authentication to trigger but can be exploited via a specially crafted HTTP POST request to achieve arbitrary code execution. Exploitation is straightforward due to lack of input validation, as demonstrated by the crash reports showing register corruption and successful return-address overwrite.

Affected products

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

Timeline

2026-10-20: disclosed

References

https://talosintelligence.com/vulnerability_reports/TALOS-2026-2395

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