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CriticalVulnerabilityCVE-2026-42020updated 25 Oct 2026, 15:22 UTC

TOTOLINK X2000R router: crafted request can run attacker code

A flaw in the web admin page of this TOTOLINK router lets someone who is logged in send a specially built request that can take control of the device. Anyone on your network or with access to the router's admin page could abuse it.

Official, 2 sources
SeverityCriticalCVSS 9.1 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Attacker logs inNeeds valid admin access to the router
  2. 2Crafted HTTP requestOversized pppoe_dns2 value sent to the web server
  3. 3Buffer overflowBoa formIpv6Setup overflows the stack
  4. 4Code executionAttacker runs commands on the router
  5. ResultAttacker controls the router

What happened

Stack-based buffer overflows in the boa web server's formIpv6Setup PPPoE handling of the TOTOLINK X2000R firmware (TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327), triggered via the pppoe_dns2 parameter, allow arbitrary code execution.

Why it is dangerous: Successful exploitation gives an attacker control of the router, which can expose internet traffic and internal devices to interception or further attack. Home and small office users with this router are at risk.

Are you affected?

You are affected if you run TOTOLINK X2000R with firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 and its web management interface is reachable by untrusted users.

TOTOLINK X2000R, firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327

What to do

  1. Check the router's firmware version and confirm whether it matches the affected build.
  2. Check the vendor (TOTOLINK) site for a firmware update and install it when available.
  3. Restrict access to the router's admin page so only trusted devices can reach it, and change the admin password.
  4. Disable remote management if it is enabled.

Timeline

  1. 20 Oct 2026, 21:17 UTC
    Publicly disclosed
  2. 20 Oct 2026, 21:17 UTC
    Reported by NVD · NVD
  3. 25 Oct 2026, 15:22 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-42020 · GHSA-vcwc-rc3q-4m7r
CVSS
9.1 / 10
EPSS
0.7% chance of exploitation within 30 days
Disclosed
20 Oct 2026, 21:17 UTC
On Zero Radar
before the radar started
Last change
25 Oct 2026, 15:22 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

TOTOLINK X2000R router: crafted request can run attacker code · Zero Radar