Auth bypass in Netis Systems Co., Ltd. Nc63 Wireless Ac1200 Router
CVE-2026-73673
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.
Vulnerability class: Broken Authentication
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Netis Systems Co., Ltd. Nc63 Wireless Ac1200 Router — versions 0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- disclosure@vulncheck.com (issue-tracking)
- disclosure@vulncheck.com (technical-description)
- disclosure@vulncheck.com (technical-description)
- disclosure@vulncheck.com (third-party-advisory)
- disclosure@vulncheck.com (issue-tracking)
- disclosure@vulncheck.com (product)
Frequently asked questions
- What is CVE-2026-73673?
- CVE-2026-73673 is a high-severity vulnerability in Netis Systems Co., Ltd. Nc63 Wireless Ac1200 Router, classified under Missing Authentication for Critical Function. CVSS score: 8.8/10. Published 2026-08-14.
- How severe is CVE-2026-73673?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2026-73673 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.