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

> Unauthenticated attackers can upload unsigned firmware to Netis NC63 routers, enabling persistent compromise and full control of the device.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** GHSA-mqjf-hpmj-9gr8

## What is CVE-2026-73673?

CVE-2026-73673 is a high-severity missing authorization vulnerability in Netis NC63 Wireless AC1200 Router, published on 14 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-73673?


## How do I fix CVE-2026-73673?

No fix has been published for CVE-2026-73673 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73673 being exploited?

There is no known exploitation of CVE-2026-73673 in the wild and no public exploit code.

Public exploit code:

- Original research and PoC for an unauthenticated firmware update vulnerability with missing cryptographic firmware authentication in Netis NC63 (github_poc): https://github.com/ozcanpng/CVE-2026-73673

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73673 and fix it if it is affected.

What it is: CVE-2026-73673 is a high-severity missing authorization vulnerability in Netis NC63 Wireless AC1200 Router, published on 14 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-73673 in the wild and no public exploit code.

Affected product: Netis NC63 Wireless AC1200 Router. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-73673/ (Markdown: https://insights.sbomify.com/CVE-2026-73673/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73673
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73673
- OSV: https://osv.dev/vulnerability/CVE-2026-73673

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-73673/
Summaries are generated and may contain mistakes; the official description above is the record.