| Title | Tenda A21 V1.0.0.0 Stack-based Buffer Overflow |
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| Description | During a security review of the Tenda A21 router firmware (version V1.0.0.0), a critical buffer overflow vulnerability was identified in the Wi-Fi schedule configuration endpoint /goform/openSchedWifi.
The vulnerability exists within the setSchedWifi function. This function retrieves user-controlled parameters schedStartTime and schedEndTime via the websGetVar interface. These values are subsequently copied into a heap-allocated buffer of fixed size (25 bytes) using the unsafe strcpy function. Since there is no length validation on the input, an attacker can provide an oversized string to overflow the buffer, leading to memory corruption, Denial of Service (DoS), or potential arbitrary code execution. |
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| Source | ⚠️ https://github.com/QIU-DIE/cve-nneeww/issues/4 |
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| User | hhsw34 (UID 91076) |
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| Submission | 02/09/2026 12:44 PM (2 months ago) |
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| Moderation | 02/20/2026 03:41 PM (11 days later) |
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| Status | Accepted |
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| VulDB entry | 347110 [Tenda A21 1.0.0.0 /goform/openSchedWifi setSchedWifi schedStartTime/schedEndTime stack-based overflow] |
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| Points | 20 |
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