CVE-2026-77217: Stack Overflow (CVSS 4.9)

Description

PLANET GS-4210-16P2S V3 firmware before 3.441b260626 contains authenticated stack buffer overflow and null pointer dereference vulnerabilities in /cgi-bin/dispatcher.cgi. The web_radiusSrv*_post family of handlers copies the radKey, radKey_0, radDftParamKey, radName, and radIp POST parameters into fixed-size stack buffers without length validation, and additionally dereferences radName and radIp without verifying their presence in the request. A remote authenticated attacker can send crafted requests to crash the CGI process or web management service, resulting in denial of service.

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CVSS v3.1 Score

4.9

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0043

Probability of exploitation

0.37%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-121 CWE-121

CWE-476 CWE-476

References

Other References

https://www.planet.com.tw/en/support/security-advisory/10 https://www.vulncheck.com/advisories/planet-gs-4210-16p2s-stack-buffer-overflow-and-null-pointer-dereference-via-dispatcher-cgi-radius-handlers

Frequently Asked Questions

What is CVE-2026-77217? +

PLANET GS-4210-16P2S V3 firmware before 3.441b260626 contains authenticated stack buffer overflow and null pointer dereference vulnerabilities in /cgi-bin/dispatcher.cgi. The web_radiusSrv*_post family of handlers copies the radKey, radKey_0, radDftParamKey, radName, and radIp POST parameters into fixed-size stack buffers without length validation, and additionally dereferences radName and radIp without verifying their presence in the request. A remote authenticated attacker can send crafted requests to crash the CGI process or web management service, resulting in denial of service. It has a CVSS v3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2026-77217? +

CVE-2026-77217 has a CVSS v3.1 score of 4.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0043, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-77217? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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