---
id: "CVE-2026-9817"
kind: "vulnerability"
aliases: ["CVE-2026-9817"]
title: "TOTOLINK X2000R router: upload handler overflow lets authenticated attacker 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: ["buffer-overflow", "embedded-firmware", "infrastructure", "router", "totolink", "x2000r"]
not_affected_if: ["auth-required", "no-web-admin-exposure", "other-firmware-version", "wan-admin-disabled"]
published_at: "2026-10-20T21:17:22+00:00"
first_seen_at: "2026-10-23T21:57:21+00:00"
updated_at: "2026-10-23T23:11:30+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9817", "first_seen_at": "2026-10-23T21:57:21+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T23:11:30+00:00"}]
---

# TOTOLINK X2000R router: upload handler overflow lets authenticated attacker run code

Stack overflow in the boa web server's /boafrm/formUploadFile on TOTOLINK X2000R: the multipart filename is copied with sprintf into a 0xc8-byte stack buffer with no length check. An attacker logged in to the admin interface can send a crafted upload and get code execution as the boa process (crash shows control of the return address). CVSS 9.1 (PR:H). Found by Cisco Talos; vendor acknowledged but no patched firmware is published as far as sources show.

_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

In the router admin UI (System / firmware info) read the firmware version. Vulnerable if it is TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327. Also check whether the admin interface is reachable from WAN or untrusted LAN/Wi-Fi.

## Fix

No fixed firmware known. Check totolink.net X2000R downloads (https://www.totolink.net/home/menu/newstpl/menu_newstpl/products/id/242.html) for a build newer than B20250421.1327. Until then: disable remote/WAN admin, restrict the admin UI to a trusted LAN, change the default admin password, and replace the device if it must be exposed.

## Timeline

- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-9817
- 2026-10-23T23:11:30+00:00 analyst — Talos TALOS-2026-2429 (2026-10-20) is the primary source: only build B20250421.1327 listed; vendor acknowledged 2026-06-25 but no fix or fixed firmware found in Talos timeline or CVE record. Aggregator 'Patched' flag (Feedly) unverified. No PoC beyond a dummy-firmware generator and crash trace in Talos; no exploitation evidence. Sibling X2000R CVEs: 9827, 9869, 9814, 9660.

## Documents

- [advisory] TALOS-2026-2429 Totolink X2000R boa formUploadFile stack-based buffer overflow https://talosintelligence.com/vulnerability_reports/TALOS-2026-2429

## From the sources

A stack-based buffer overflow vulnerability exists in the boa formUploadFile 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 this vulnerability.

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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_