# CVE-2026-77217: PLANET GS-4210-16P2S V3 stack buffer overflow in RADIUS handlers

Source: https://junglewise.ai/threats/cve-2026-77217-planet-gs-4210-16p2s-v3-stack-buffer-overflow-in-radius-handlers  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-28. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-77217 · Severity: medium · CVSS 4.9 · Published 2026-08-28

PLANET GS-4210-16P2S V3 is a managed gigabit network switch used to control and monitor enterprise network infrastructure. The device's web management interface contains stack buffer overflow and null pointer dereference flaws in the RADIUS server configuration handlers that allow an authenticated administrator to crash the web service, disrupting management access and potentially allowing denial of service attacks against network operations.

Technologies: [PLANET GS-4210-16P2S V3](https://junglewise.ai/threats/technologies/gs-4210-16p2s-v3). Vendors: [PLANET](https://junglewise.ai/threats/vendors/planet).

## Quick answers

**Is CVE-2026-77217 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-77217 being exploited in the wild.

**How severe is CVE-2026-77217?** Medium severity, with a CVSS score of 4.9, published 28 August 2026.

**Which products and versions are affected?** PLANET GS-4210-16P2S V3 before 3.441b260626.

**Is there a fix for CVE-2026-77217?** A patch was published on 2026-08-28: Firmware 3.441b260626 and later Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-77217 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-77217?** Check whether you run PLANET GS-4210-16P2S V3 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a stack buffer overflow combined with null pointer dereference in the web_radiusSrv*_post handler family (cmd=7936, 7938, 7940) within /cgi-bin/dispatcher.cgi. The POST parameters radKey, radKey_0, radDftParamKey, radName, and radIp are copied into fixed-size stack buffers without length validation; additionally, radName and radIp are dereferenced without verifying their presence in the request, leading to potential crashes. The flaw requires authentication at the administrator privilege level and network reachability to the management interface. Exploitation allows an authenticated remote attacker to crash the CGI process or web management service, denying legitimate administrative access. Firmware version 3.441b260626 and later contain the patch.

## Affected products

- PLANET GS-4210-16P2S V3 before 3.441b260626

## Timeline

- 2026-08-28: disclosed
- 2026-08-28: patched: Firmware 3.441b260626 and later

## References

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

## Related threats

- [PLANET GS-4210-16P2S V3 stack buffer overflow in dispatcher.cgi](https://junglewise.ai/threats/cve-2026-77218-planet-gs-4210-16p2s-v3-stack-buffer-overflow-in-dispatcher-cgi)
- [PLANET GS-4210-16P2S V3 stack buffer overflow in dispatcher.cgi handlers](https://junglewise.ai/threats/cve-2026-75126-planet-gs-4210-16p2s-v3-stack-buffer-overflow-in-dispatcher-cgi)
- [PLANET GS-4210-16P2S V3 null pointer dereference in dispatcher.cgi](https://junglewise.ai/threats/cve-2026-75125-planet-gs-4210-16p2s-v3-null-pointer-dereference-in-dispatcher)
- [PLANET GS-4210-16P2S V3 pre-authentication memory corruption](https://junglewise.ai/threats/cve-2026-75124-planet-gs-4210-16p2s-v3-pre-authentication-memory-corruption)
- [PLANET GS-4210-16P2S V3 OS command injection in dispatcher.cgi](https://junglewise.ai/threats/cve-2026-75123-planet-gs-4210-16p2s-v3-os-command-injection-in-dispatcher-cgi)