CVE-2026-5021
Stack-Based Buffer Overflow in Tenda F453 HTTPD Allows Remote Exploit
Publication date: 2026-03-29
Last updated on: 2026-03-30
Assigner: VulDB
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| tenda | f453_firmware | 1.0.0.3 |
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-787 | The product writes data past the end, or before the beginning, of the intended buffer. |
| CWE-121 | A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
The CVE-2026-5021 vulnerability affects the Tenda F453 router, version V1.0.0.3, and is a stack-based buffer overflow in the httpd service.
Specifically, the overflow occurs in the fromPPTPUserSetting function, which processes a user-supplied parameter named "delno." When "delno" is not empty, its value is assigned to a variable s_1, which is then passed to another variable s_3.
The variable s_3 is subsequently used as an argument in a call to the sprintf function without any bounds checking. This lack of length validation allows an attacker to overflow the stack buffer s_1.
Exploitation can be achieved by sending a crafted HTTP POST request to the endpoint /goform/PPTPUserSetting with an excessively long "delno" parameter, causing the overflow.
How can this vulnerability impact me? :
Successful exploitation of this vulnerability can lead to denial of service (DoS) or remote code execution (RCE) on the affected device.
This means an attacker could crash the router or potentially take control of it remotely, which could disrupt network connectivity or allow unauthorized access.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring for unusual or malicious HTTP POST requests sent to the endpoint /goform/PPTPUserSetting on Tenda F453 routers running version 1.0.0.3.
Specifically, detection involves looking for POST requests containing an excessively long or malformed "delno" parameter, which is used to trigger the stack-based buffer overflow.
A practical approach is to capture and inspect HTTP traffic targeting the router, focusing on requests to /goform/PPTPUserSetting.
- Use network packet capture tools like tcpdump or Wireshark to filter HTTP POST requests to /goform/PPTPUserSetting.
- Example tcpdump command to capture relevant traffic: tcpdump -i <interface> -A 'tcp port 80 and (((ip dst <router_ip>) and (tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x504f5354)))'
- Use grep or similar tools to search captured HTTP POST data for the "delno" parameter with unusually long values.
- Example command to test the vulnerability manually: send a crafted HTTP POST request with a long "delno" parameter to /goform/PPTPUserSetting using curl or a similar tool.
- Example curl command: curl -X POST http://<router_ip>/goform/PPTPUserSetting -d "delno=$(python3 -c 'print("a"*1000)')"
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include restricting access to the vulnerable endpoint and preventing exploitation attempts.
- Block or filter incoming HTTP POST requests to /goform/PPTPUserSetting on the affected Tenda F453 router from untrusted networks.
- Limit network exposure of the router’s management interface by placing it behind a firewall or restricting access to trusted IP addresses only.
- Monitor logs and network traffic for suspicious requests containing long or malformed "delno" parameters.
- If possible, update the router firmware to a version that patches this vulnerability once available from the vendor.
Until a patch is applied, avoid exposing the router’s management interface to the internet and consider disabling PPTP user settings if not needed.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.