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CriticalVulnerabilityCVE-2026-9817updated 25 Oct 2026, 15:24 UTC

TOTOLINK X2000R router can be taken over through its file upload feature

A specially crafted web request sent to this router's file upload feature can make it run attacker code. The attacker needs to be logged in to the router first.

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 credentials for the router
  2. 2Crafted upload requestOversized data sent to formUploadFile
  3. 3Stack buffer overflowInput overwrites memory on the stack
  4. 4Code executionAttacker code runs on the router
  5. ResultAttacker controls the router

What happened

A stack-based buffer overflow in the boa formUploadFile handler of the TOTOLINK X2000R allows arbitrary code execution via a crafted authenticated HTTP request.

Why it is dangerous: An attacker who can log in to the router can run their own code on it, which could let them control the device, observe or redirect traffic, and reach other devices on the network.

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 whether your router runs TOTOLINK X2000R firmware B20250421.1327 and look for an updated firmware from TOTOLINK
  2. Install the vendor firmware update as soon as it is available
  3. Limit access to the router's web management page to trusted devices and change the admin password
  4. Do not expose the router's management interface to the internet

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, 15:24 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-9817 · GHSA-4x89-c5gq-3rg8
CVSS
9.1 / 10
EPSS
0.5% 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, 15:24 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 can be taken over through its file upload feature · Zero Radar