Root command execution via stored DMZ address
Published Jan 29, 2026 · Updated Jan 29, 2026
Command injection in Tenda AC21 1.1.1.1, 1.dmzip, and 16.03.08.16 allows remote authenticated users to execute commands as root. The mDMZSetCfg handler stores the dmzIp value in NVRAM after inet_addr accepts an IPv4 prefix with trailing shell metacharacters, and netctrl later concatenates that value into a firewall command for system() or popen(). Administrative web-interface authentication is required; exploitation can reboot the router, alter firewall rules, or persist commands for later execution.
Summary
What happened
Command injection in Tenda AC21 1.1.1.1, 1.dmzip, and 16.03.08.16 allows remote authenticated users to execute commands as root. The mDMZSetCfg handler stores the dmzIp value in NVRAM after inet_addr accepts an IPv4 prefix with trailing shell metacharacters, and netctrl later concatenates that value into a firewall command for system() or popen(). Administrative web-interface authentication is required; exploitation can reboot the router, alter firewall rules, or persist commands for later execution.
The record
- CVE
- CVE-2026-1638
- Published
- Jan 29, 2026
- Updated
- Jan 29, 2026
- Vendor
- Shenzhen Tenda Technology Co., Ltd.
- Product
- AC21 Firmware
- Classifications
- CWE-74, CWE-77, T1059.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 29, 2026CVE publishedPublication date reported by the CVE source.
- Jan 29, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.1.1.1
- Affected versionversion=16.03.08.16
- Affected versionversion=1.dmzip
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- Authenticated mDMZSetCfg reboot proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo