CVE-2026-8138
Stack-Based Buffer Overflow in Tenda CX12L Router
Publication date: 2026-05-08
Last updated on: 2026-05-08
Assigner: VulDB
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| tenda | cx12l | 16.03.53.12 |
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-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?
CVE-2026-8138 is a critical buffer overflow vulnerability found in the Tenda Router CX12L running firmware version V16.03.53.12. The flaw exists in the /goform/SetPptpServerCfg endpoint, specifically within the formSetPPTPServer() function. The vulnerability arises because the sscanf function improperly parses the startIp parameter without proper bounds checking, allowing an attacker to supply an excessively large input.
This improper input handling leads to a stack-based buffer overflow, which can overwrite stack memory and cause application crashes, memory corruption, or even arbitrary code execution. The attack can be executed remotely and does not require authentication.
How can this vulnerability impact me? :
This vulnerability can have severe impacts including denial of service, information leakage, or full device takeover. Because it allows remote exploitation without authentication, an attacker can crash the device, corrupt memory, or execute arbitrary code, potentially gaining complete control over the affected router.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring for suspicious POST requests to the `/goform/SetPptpServerCfg` endpoint, specifically those containing a malformed or excessively large `startIp` parameter.
A proof-of-concept exploit sends a malformed `startIp` parameter via a POST request, which can be used as a basis for detection.
- Use network monitoring tools or intrusion detection systems (IDS) to look for POST requests targeting `/goform/SetPptpServerCfg`.
- Example command using curl to test the vulnerability (for detection purposes only): curl -X POST http://<router-ip>/goform/SetPptpServerCfg -d "startIp=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
- Use packet capture tools like tcpdump or Wireshark to filter HTTP POST requests to `/goform/SetPptpServerCfg` and inspect the `startIp` parameter.
What immediate steps should I take to mitigate this vulnerability?
Immediate remediation steps include replacing unsafe parsing functions, implementing strict input validation, and applying least privilege principles.
Additional mitigation measures involve adopting secure coding practices and enabling compiler protections such as stack canaries and Address Space Layout Randomization (ASLR).
Since the vulnerability can be exploited remotely without authentication, it is critical to update the firmware to a patched version if available or restrict access to the vulnerable endpoint.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability in Tenda CX12L allows remote attackers to execute arbitrary code or cause denial of service, potentially leading to unauthorized access or data leakage.
Such security weaknesses can impact compliance with standards like GDPR and HIPAA, which require protection of personal and sensitive data against unauthorized access and breaches.
Failure to address this vulnerability could result in violations of these regulations due to compromised confidentiality, integrity, and availability of data handled by the affected device.