CVE-2026-77218
Received Received - Intake

Authenticated Stack Buffer Overflow in PLANET GS-4210-16P2S Firmware

Vulnerability report for CVE-2026-77218, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: VulnCheck

Description

PLANET GS-4210-16P2S 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.

CVSS Scores

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Meta Information

Published
2026-08-28
Last Modified
2026-08-28
Generated
2026-08-29
AI Q&A
2026-08-29
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
planet gs-4210-16p2s to 3.441b260626 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-121 A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Attack-Flow Graph

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Executive Summary

This vulnerability is a stack buffer overflow in PLANET GS-4210-16P2S firmware before version 3.441b260626. It affects three credential handlers in /cgi-bin/dispatcher.cgi that copy POST parameters into fixed-size stack buffers without length validation. A remote authenticated attacker can exploit this by sending crafted requests to cause buffer overflows, crashing the CGI process or web management service and leading to denial of service.

Detection Guidance

To detect this vulnerability, monitor for crashes in the CGI process or web management service of PLANET GS-4210-16P2S devices. Check for unusual POST requests to /cgi-bin/dispatcher.cgi with parameters usrPass, enbPass, usrName, or usrPass exceeding expected lengths. Review logs for authentication-related errors or service interruptions.

Impact Analysis

If you use the affected PLANET GS-4210-16P2S firmware, an attacker with valid credentials could exploit this flaw to crash the device's web management interface or CGI processes. This would disrupt network management and potentially take the device offline, causing downtime for connected systems.

Mitigation Strategies

Immediately update the firmware to version 3.441b260626 or later. If an update is not immediately available, restrict access to the web management interface and disable unnecessary services. Monitor network traffic for suspicious POST requests to /cgi-bin/dispatcher.cgi.

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