---
id: CVE-2026-77218
title: >-
  PLANET GS-4210-16P2S V3 firmware before 3.441b260626 contains authenticated
  stack buffer overflow vulnerabilities in /cgi-bin/dispatcher.cgi
summary: >-
  PLANET GS-4210-16P2S V3 firmware before 3.441b260626 contains authenticated
  stack buffer overflow vulnerabilities in /cgi-bin/dispatcher.cgi. The
  web_login_first_post handler copies the usrPass POST parameter into a
  fixed-size stack buff…
severity: medium
cvss: 4.9
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-121
published: '2026-08-28'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:20:22.260'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77218'
references:
  - url: 'https://www.planet.com.tw/en/support/security-advisory/10'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/planet-gs-4210-16p2s-stack-buffer-overflow-via-dispatcher-cgi-credential-handlers
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00572
epssPercentile: 0.44956
ingestedAt: '2026-09-08T21:11:12.287Z'
---

## Overview

PLANET GS-4210-16P2S V3 firmware before 3.441b260626 contains authenticated stack buffer overflow vulnerabilities in /cgi-bin/dispatcher.cgi. The web_login_first_post handler copies the usrPass POST parameter into a fixed-size stack buffer without length validation, the web_sys_enablePasswd_post handler copies the enbPass POST parameter into a fixed-size stack buffer without length validation, and the web_sys_localUser_post handler copies the usrName and usrPass POST parameters into fixed-size stack buffers without length validation. A remote authenticated attacker can send a crafted request to crash the CGI process or web management service, resulting in denial of service.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.