Unauthenticated root code execution via unbounded Base64 decode
Published Aug 24, 2026 · Updated Aug 24, 2026
Stack-based buffer overflow in Netis NC63 firmware through 3.0.0.3327 allows remote attackers to execute code through the login endpoint. The /bin/netis.cgi handler decodes an attacker-controlled Base64 password into a 64-byte stack buffer without enforcing the destination capacity, overwriting the saved return address. Authentication is not required because decoding precedes credential comparison, and successful exploitation runs commands as root under the Boa CGI configuration.
Summary
What happened
Stack-based buffer overflow in Netis NC63 firmware through 3.0.0.3327 allows remote attackers to execute code through the login endpoint. The /bin/netis.cgi handler decodes an attacker-controlled Base64 password into a 64-byte stack buffer without enforcing the destination capacity, overwriting the saved return address. Authentication is not required because decoding precedes credential comparison, and successful exploitation runs commands as root under the Boa CGI configuration.
The record
- CVE
- CVE-2026-76070
- Published
- Aug 24, 2026
- Updated
- Aug 24, 2026
- Vendor
- Netis Systems Co., Ltd.
- Product
- Netis NC63
- Classifications
- CWE-121, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 24, 2026CVE publishedPublication date reported by the CVE source.
- Aug 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=3.0.0.3327
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- CVE-2026-76070 non-destructive crash-pattern PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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