---
id: "CVE-2026-9659"
kind: "vulnerability"
aliases: ["CVE-2026-9659"]
title: "TOTOLINK X2000R router: stack overflow in formFilter lets attacker run code"
severity: "critical"
cvss: 9.1
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "TOTOLINK X2000R", "fixed": [], "affected": "TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327", "ecosystem": "firmware"}]
ecosystems: []
tags: ["boa", "embedded-firmware", "infrastructure", "router", "self-hosted", "totolink", "x2000r"]
not_affected_if: ["auth-required", "no-admin-web-interface-exposed", "no-wan-admin", "other-firmware-version", "other-firmware-versions"]
published_at: "2026-10-20T21:17:22+00:00"
first_seen_at: "2026-10-23T21:57:21+00:00"
updated_at: "2026-10-23T23:12:39+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9659", "first_seen_at": "2026-10-23T21:57:21+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T23:12:39+00:00"}]
---

# TOTOLINK X2000R router: stack overflow in formFilter lets attacker run code

Authenticated stack buffer overflows in the boa web server's formFilter handler (vpnUser parameter) on TOTOLINK X2000R firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327. A logged-in admin sending a crafted HTTP request can run code on the router. CVSS 9.1. Part of a batch of ~30 Talos CVEs against this one build. No fix published, no known exploitation or PoC.

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

## Affected

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

## How to check

Log in to the router admin UI and read the firmware version. Build TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 is confirmed vulnerable; other builds are untested (unknown). Confirm the admin web interface is not reachable from the WAN side.

## Fix

No fixed firmware published as of 2026-10-23 (unknown). Mitigate: set a long unique admin password, disable remote/WAN administration, restrict admin UI to management hosts. Install a patched build only from totolink.net once released. If compromise is suspected, reflash from an official image or replace the unit and rotate Wi-Fi/VPN/PPPoE secrets.

## Timeline

- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-9659
- 2026-10-23T23:12:39+00:00 analyst — Talos CNA record (cve.org), VulDB and OpenCVE: only build B20250421.1327 named; authenticated (PR:H) per description; no vendor fix/advisory found, no PoC (VulDB: none), not in KEV. Sibling of CVE-2026-9660 (vpnPassword) in a batch of ~30 Talos X2000R CVEs. Not checked: TOTOLINK support site, Talos report page, social posts.

## Documents

- [advisory] CVE Record: CVE-2026-9659 (Talos CNA) https://www.cve.org/CVERecord?id=CVE-2026-9659
- [mentions] VDB-424076 Totolink X2000R formFilter vpnUser stack-based overflow https://vuldb.com/vuln/424076
- [mentions] OpenCVE CVE-2026-9659 https://app.opencve.io/cve/CVE-2026-9659

## From the sources

Multiple exploitable stack-based buffer overflow vulnerabilities exist in the boa formFilter 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 deals with the vpnUser parameter.

---

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