| 제목 | Wavlink NU516U1 V251208 Stack-based Buffer Overflow |
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| 설명 | ## **Stack-based Buffer Overflow in Wavlink NU516U1 (V251208) via "time_zone" parameter on adm.cgi interface of adm.cgi component**
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### **Overview**
- **Vendor**: Wavlink
- **Product**: NU516U1
- **Version**: WAVLINK-NU516U1-A-WO-20251208-BYFM
- **Vulnerability Type**: Stack-based Buffer Overflow
- **Product Purpose**: USB Printer Server
- **Firmware Download**: https://docs.wavlink.xyz/Firmware/?category=USB+Printer+Server&model=all
- **Default Password**: `admin`
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### **Vulnerability Information**
- **Vulnerable Function**: `sub_40785C` (Handles NTP and Timezone settings)
- **Vulnerability Point**: `strcpy(v31, v4);`
- **Trigger Parameter**: `time_zone` (corresponds to `v4`)
- **Prerequisite**: `dstEnabled` must be set to `"1"` to enter the vulnerable branch.
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### **Vulnerability Description**
Under the MIPS 32-bit architecture, this function allocates a fixed-size buffer `v31` (16 bytes) on the stack. The program uses `sub_40B2F8` to extract the `time_zone` string directly from the user's POST request. Prior to executing the `strcpy` copy operation, the program performs no validation on the length of the user-supplied string. An attacker can send a string exceeding 15 bytes (leaving 1 byte for `\x00`) to break the boundaries of `v31`, sequentially overwriting adjacent local variables, saved register values, and finally the return address (`$ra`) on the stack. When the function attempts to return, the execution flow is hijacked to an address controlled by the attacker. |
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| 원천 | ⚠️ https://github.com/Wlz1112/Wavlink-NU516U1-V251208-/blob/main/time_zone.md |
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| 사용자 | haimianbaobao (UID 94979) |
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| 제출 | 2026. 02. 03. PM 04:25 (3 개월 ago) |
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| 모더레이션 | 2026. 02. 15. PM 08:40 (12 days later) |
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| 상태 | 수락 |
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| VulDB 항목 | 346172 [Wavlink WL-NU516U1 20251208 /cgi-bin/adm.cgi sub_40785C time_zone 메모리 손상] |
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| 포인트들 | 20 |
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