---
id: "CVE-2026-123957"
page: "https://infrastack.ai/live/CVE-2026-123957"
kind: "vulnerability"
aliases: ["CVE-2026-123957"]
title: "TOTOLINK CA300-PoE: remote buffer overflow in setIpQosRules lets attackers run code"
severity: "critical"
cvss: 9.9
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "CA300-PoE", "fixed": [], "affected": "6.2c.884", "ecosystem": "vendor"}]
ecosystems: []
tags: ["auth-required", "ca300-poe", "embedded", "firmware", "infrastructure", "router", "totolink"]
not_affected_if: ["management-not-exposed", "other-firmware-version"]
published_at: "2026-11-07T09:17:14+00:00"
first_seen_at: "2026-11-07T09:46:25+00:00"
updated_at: "2026-11-07T09:48:42+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123957", "first_seen_at": "2026-11-07T09:46:25+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123957", "first_seen_at": "2026-11-07T09:48:42+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/CVE-2026-123957"]}]
exploit_sources: []
---

# TOTOLINK CA300-PoE: remote buffer overflow in setIpQosRules lets attackers run code

Link for people: https://infrastack.ai/live/CVE-2026-123957 (this .md is for agents)

TOTOLINK CA300-PoE firmware 6.2c.884 has a buffer overflow in the setIpQosRules function of /cgi-bin/cstecgi.cgi, triggered by an oversized ipStart argument. The exploit has been publicly disclosed, so an attacker reaching the device over the network could crash it or likely run code on it.

_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

- Log in to the CA300-PoE admin page and read the firmware version; 6.2c.884 is the version named in NVD.
- Check whether the web management interface (/cgi-bin/cstecgi.cgi) is reachable from the internet or untrusted networks.
- Other firmware versions are not stated as affected or unaffected; the sources do not say.

## Timeline

- 2026-11-07T09:46:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123957
- 2026-11-07T09:48:42+00:00 analyst https://nvd.nist.gov/vuln/detail/CVE-2026-123957 — Only NVD/CNA (VulDB) record found; no TOTOLINK advisory or fixed firmware located, no PoC link for this CVE (sibling setIpQosRules PoCs are other models). CVSS vector has PR:L, so a login is likely needed, unconfirmed. Nothing verified.

## Documents

- [describes] NVD: CVE-2026-123957 https://nvd.nist.gov/vuln/detail/CVE-2026-123957

## From the sources

A vulnerability was determined in TOTOLINK CA300-PoE 6.2c.884. Impacted is the function setIpQosRules of the file /cgi-bin/cstecgi.cgi. This manipulation of the argument ipStart causes buffer overflow. It is possible to initiate the attack remotely. The exploit has been publicly disclosed and may be utilized.

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