CVE-2026-76071: Stack-based Buffer Overflow in Netis Systems NC63
Description
Netis NC63 firmware up to version 3.0.0.3327 contains a critical stack-based buffer overflow vulnerability. This flaw allows unauthenticated remote attackers to overwrite the saved stack state by sending an oversized destHost parameter to the ipFilterList=mod action in netis.cgi. The vulnerability arises from unsafe sscanf conversions that copy user input into fixed-size stack buffers before authentication is checked. Exploitation can lead to remote code execution with root privileges due to the Boa web server running CGI scripts as root.
CVSS v4.0
Score 9.3critical
Affected software
Netis Systems
NC63
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-76071 is a stack-based buffer overflow in Netis NC63 firmware through version 3.0.0.3327. The vulnerability occurs because the ipFilterList=mod action in netis.cgi uses widthless sscanf conversions to copy an attacker-controlled destHost parameter into fixed-size stack buffers without prior authentication. This allows unauthenticated remote attackers to overwrite the saved stack state, potentially leading to remote code execution as root. The Boa web server executes CGI environment scripts with root privileges, increasing the severity of this flaw.
Potential Impact
An unauthenticated remote attacker can exploit this buffer overflow to execute arbitrary code with root privileges on the affected device. This compromises the device's confidentiality, integrity, and availability, allowing full control over the Netis NC63 router.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict network access to the device's management interface to trusted sources only to reduce exposure.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-18T21:04:48.503Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a8c68d6acd9273b49c4d34f
Added to database: 08/24/2026, 15:52:54 UTC
Last enriched: 09/10/2026, 10:22:42 UTC
Last updated: 10/08/2026, 06:48:19 UTC
Views: 80
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