---
id: "CVE-2026-123959"
page: "https://infrastack.ai/live/CVE-2026-123959"
kind: "vulnerability"
aliases: ["CVE-2026-123959"]
title: "TOTOLINK CA300-PoE: setLanguageCfg langType argument buffer overflow allows remote attack"
severity: "critical"
cvss: 9.1
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "CA300-PoE", "fixed": [], "affected": "6.2c.884", "ecosystem": "vendor"}]
ecosystems: []
tags: ["ca300-poe", "embedded", "infrastructure", "iot", "totolink"]
not_affected_if: ["no-network-exposure", "other-firmware-version"]
published_at: "2026-11-07T10:17:12+00:00"
first_seen_at: "2026-11-07T10:46:41+00:00"
updated_at: "2026-11-07T10:49:35+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123959", "first_seen_at": "2026-11-07T10:46:41+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123959", "first_seen_at": "2026-11-07T10:49:35+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/CVE-2026-123959"]}]
exploit_sources: []
---

# TOTOLINK CA300-PoE: setLanguageCfg langType argument buffer overflow allows remote attack

Link for people: https://infrastack.ai/live/CVE-2026-123959 (this .md is for agents)

The TOTOLINK CA300-PoE 6.2c.884 web management CGI function setLanguageCfg in /cgi-bin/cstecgi.cgi overflows a buffer when the langType argument is manipulated. A remote attacker can trigger it over the network, and a public exploit has been released.

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

## Affected

- vendor:CA300-PoE affected 6.2c.884 fixed no fixed version listed

## How to check

Look up the firmware version on the device's web admin page (System/Status); 6.2c.884 is the version named in the CVE. Check whether the admin web interface (/cgi-bin/cstecgi.cgi) is reachable from the internet or untrusted networks. No fixed version or vendor check command was found. Also check other CA300-PoE builds, since only 6.2c.884 is named.

## Timeline

- 2026-11-07T10:46:41+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123959
- 2026-11-07T10:49:35+00:00 analyst https://nvd.nist.gov/vuln/detail/CVE-2026-123959 — Only NVD/aggregator text found (CVE description, CNA vuldb, CVSS 4.0 vector PR:H suggests auth needed, not confirmed). No TOTOLINK vendor advisory or fixed firmware found; no PoC link found despite 'exploit public' claim. Nothing verified. Fix unknown; settle by checking the TOTOLINK download page for CA300-PoE and the VulDB entry. Sibling CVEs 123957/123958 same product.

## Documents

- [describes] NVD CVE-2026-123959 https://nvd.nist.gov/vuln/detail/CVE-2026-123959

## From the sources

A security flaw has been discovered in TOTOLINK CA300-PoE 6.2c.884. The impacted element is the function setLanguageCfg of the file /cgi-bin/cstecgi.cgi. Performing a manipulation of the argument langType results in buffer overflow. The attack can be initiated remotely. The exploit has been released to the public and may be used for attacks.

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