PLANET GS-5220-8P2T2S Stack Buffer Overflow via webstax_auth Cookie

published 2026-11-13 yesterday modified 2026-11-13 yesterday also EUVD-2026-125515

cvss: 9.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits: 0; none known

PLANET GS-5220-8P2T2S (hardware version 3.0) firmware versions before 3.2412b261008 contains a stack-based buffer overflow vulnerability that allows unauthenticated attackers to corrupt stack memory by submitting an oversized webstax_auth HTTP Cookie value that is copied into a fixed-size stack buffer without length validation. Attackers can send a crafted unauthenticated HTTP request with an oversized cookie to overwrite the saved return address and corrupt stack memory, leading to memory corruption and potential denial of service on the device.

Patch / fix

fixed in 1 links 1

PLANET Technology Corp. PLANET GS-5220-8P2T2S 3.2412b261008

planet.com.tw/en/support/security-advisory/12 advisory

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Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by	version	score	vector
CNA	4.0	9.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA	4.0	9.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

PLANET Technology Corp. PLANET GS-5220-8P2T2S

Classification

Weakness

CWE-121 Stack-based Buffer Overflow

References

planet.com.tw /en/support/security-advisory/12
vendor-advisory, patch
vulncheck.com /advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie
third-party-advisory

Sources

CVE List CVE-2026-109445
NVD CVE-2026-109445

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