| Title | Wavlink NU516U1 V251208) Command Injection |
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| Description | # The DMZ function of Wavlink NU516U1 (V251208) firewall.cgi component has a remote command execution vulnerability.
### Overview
Supplier: Wavlink
Product: NU516U1 Version: WAVLINK-NU516U1-A-WO-20251208-BYFM
Type: command injection
### Vulnerability description
A command injection vulnerability exists in the `/cgi-bin/firewall.cgi` component in Wavlink NU516U1 router firmware (version M16U1_V251208). The vulnerability is located in the `sub_4017F0` function that handles DMZ settings. Although the manufacturer introduced the filtering function `sub_405B2C` in an attempt to fix the vulnerability of the old version (M16U1_V240425), the blacklist filtering mechanism is not rigorous and misses the key command delimiter semicolon (`;`). An authenticated remote attacker can bypass input validation by constructing a malicious `dmz_flag` parameter containing a semicolon, and use the `sprintf` function to splice arbitrary shell commands into a system call for execution, thereby taking full control of the device with root privileges. |
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| Source | ⚠️ https://github.com/Wlz1112/Wavlink-NU516U1-V251208-/blob/main/wavlink_DMZ.md |
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| User | haimianbaobao (UID 94979) |
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| Submission | 02/03/2026 13:15 (4 months ago) |
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| Moderation | 02/15/2026 20:35 (12 days later) |
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| Status | Duplicate |
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| VulDB entry | 325827 [Wavlink NU516U1 M16U1_V240425 /cgi-bin/firewall.cgi sub_401778 dmz_flag command injection] |
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| Points | 0 |
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