---
id: "CVE-2026-42026"
kind: "vulnerability"
aliases: ["CVE-2026-42026"]
title: "TOTOLINK X2000R router: overflow in IPv6 setup lets attackers run code"
severity: "critical"
cvss: 9.1
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "X2000R", "fixed": [], "affected": "TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327", "ecosystem": "vendor"}]
ecosystems: []
tags: ["infrastructure", "iot", "router", "self-hosted", "totolink", "x2000r"]
not_affected_if: ["auth-required", "other-firmware-versions", "wan-admin-disabled"]
published_at: "2026-10-20T21:17:19+00:00"
first_seen_at: "2026-10-23T21:57:21+00:00"
updated_at: "2026-10-23T23:12:29+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42026", "first_seen_at": "2026-10-23T21:57:21+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T23:12:29+00:00"}]
---

# TOTOLINK X2000R router: overflow in IPv6 setup lets attackers run code

The boa web server's formIpv6Setup handler on the TOTOLINK X2000R router copies the dhcp_dns2 parameter into a fixed-size stack buffer without checking its length. An attacker with a logged-in session can send a crafted HTTP request to run arbitrary code on the router.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:X2000R affected TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 fixed ?

## How to check

Log in to the router admin page and read the firmware version; TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 is the only build confirmed vulnerable (other builds untested, not confirmed safe). Check whether the admin web interface (boa, /boafrm/*) is reachable from WAN or from untrusted LAN/guest segments.

## Fix

No fixed firmware published as of 2026-10-23 (unknown; check totolink.net X2000R product page https://www.totolink.net/home/menu/newstpl/menu_newstpl/products/id/242.html). Mitigate: disable remote/WAN web administration, restrict admin UI to a trusted LAN, change default admin password, keep untrusted users off the LAN.

## Timeline

- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-42026
- 2026-10-23T23:12:29+00:00 analyst — Read Talos TALOS-2026-2396 (primary, shared with sibling CVE-2026-42025 dhcp_dns1): unbounded strcpy of dhcp_dns2 in /boafrm/formIpv6Setup; needs login, wan_enable set and OriginType=2. No vendor fix or patched firmware published in any source; no PoC/exploitation found; no X post search done (obscure).

## Documents

- [advisory] TALOS-2026-2396: Totolink X2000R boa formIpv6Setup dhcp_dns stack-based buffer overflows https://talosintelligence.com/vulnerability_reports/TALOS-2026-2396

## From the sources

Multiple exploitable stack-based buffer overflow vulnerabilities exist in the boa formIpv6Setup dhcp_dns functionality of X2000R (version(s): TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327). A specially crafted HTTP request can lead to arbitrary code execution. An attacker can make an authenticated HTTP request to trigger these vulnerabilities. This vulnerability concerns the dhcp_dns2 parameter.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_