CVE-2025-11091
BaseFortify
Publication date: 2025-09-28
Last updated on: 2025-10-03
Assigner: VulDB
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| tenda | ac21_firmware | to 16.03.08.16 (inc) |
| tenda | ac21 | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-119 | The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. |
| CWE-120 | The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a buffer overflow in the Tenda AC21 router firmware (up to version 16.03.08.16) occurring in the function sscanf within the /goform/SetStaticRouteCfg endpoint. The sscanf function parses input without proper bounds checking, allowing an attacker to send a specially crafted HTTP POST request with an excessively long parameter. This causes a stack-based buffer overflow, which can lead to denial of service or potentially remote code execution on the device. [1, 2, 3]
How can this vulnerability impact me? :
Exploitation of this vulnerability can impact the confidentiality, integrity, and availability of the affected Tenda AC21 router. An attacker can remotely cause a denial of service (DoS), making the device unavailable, or potentially execute arbitrary code remotely (remote code execution), which could allow full control over the device. [1, 2, 3]
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring HTTP POST requests sent to the endpoint /goform/SetStaticRouteCfg on Tenda AC21 routers running vulnerable firmware versions. Specifically, look for unusually long or malformed 'list' parameters in the POST data that could trigger the buffer overflow. A detection approach could involve capturing network traffic and filtering for POST requests to /goform/SetStaticRouteCfg with suspiciously large payloads. For example, using tcpdump or tshark: 1) Capture traffic: tcpdump -i <interface> -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' 2) Filter HTTP POST requests to the vulnerable endpoint and inspect the 'list' parameter for abnormal length or content. Alternatively, use tools like Wireshark with display filter: http.request.method == "POST" && http.request.uri contains "/goform/SetStaticRouteCfg". There is a publicly available proof-of-concept exploit that sends a long string of 'a' characters in the 'list' parameter, which can be used as a test to verify if the device is vulnerable. [1, 3]
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include restricting or blocking remote HTTP POST requests to the /goform/SetStaticRouteCfg endpoint on affected Tenda AC21 routers to prevent exploitation. Since no known countermeasures or patches are currently available, it is recommended to replace the affected device with a non-vulnerable alternative or upgrade the firmware if a fixed version becomes available. Additionally, implementing network-level protections such as firewall rules to limit access to the router's management interface and monitoring for exploit attempts can reduce risk. [2]