Stack-Based Buffer Overflow in Netis NC63 Firmware
CVE-2026-76070

9.3CRITICAL

Key Information:

Vendor

Netis Systems

Status
Nc63
Vendor
CVE Published:
24 August 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-76070?

The Netis NC63 firmware version V3.0.0.3327 contains a vulnerability due to a stack-based buffer overflow. This issue arises when an attacker submits an oversized Base64-encoded password to the login handler in /bin/netis.cgi. The vulnerability enables unauthenticated remote attackers to exploit the flawed Base64 decoding process, which lacks proper output length validation concerning the fixed-size stack buffer. Once exploited, this can lead to remote code execution with root privileges, as the Boa web server executes CGI environment scripts with elevated authority.

Affected Version(s)

NC63 0 <= 3.0.0.3327

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-76070 - Proof of Concept

CVE-2026-76070
Created by ozcanpng

References

https://ozcanpng.dev/blog/cve-2026-76070-netis-nc63-login...
technical-descriptionexploit
https://github.com/ozcanpng/CVE-2026-76070
technical-descriptionexploit
https://www.netis-systems.com/products/NC63.html
product

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Özcan Ersan (@ozcanpng)
.