CVE-2025-68706 – One Malicious Web Request Can Crash or Compromise KuWFi Routers

Aegiron 8 mins0

CVE ID: CVE-2025-68706
Vulnerability Type: Stack-based Buffer Overflow
Affected Component: GoAhead-Webs HTTP daemon
Affected Product: KuWFi 4G LTE AC900 Router
Affected Firmware: v1.0.13
CVSS v3.1 Score: 8.8 (High)
Severity: High
Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Impact: Remote Denial of Service (DoS), Potential Remote Code Execution (RCE)

Exploitability: High
Exploit Availability: No public exploit published at the time of writing, but exploitation is straightforward and practical for skilled attackers
Authentication Required: No
Patch Status: Vendor patch available

Overview

CVE-2025-68706 is a serious memory corruption vulnerability affecting the embedded web management interface of the KuWFi 4G LTE AC900 router. The issue exists in the GoAhead-Webs HTTP daemon, which is responsible for handling configuration requests through the router’s web interface.

The flaw is caused by unsafe handling of user input in the /goform/formMultiApnSetting endpoint. Specifically, a user-supplied parameter named pincode is copied into a fixed-size stack buffer using the unsafe sprintf() function, without enforcing any length checks. This allows attackers to overwrite stack memory by sending an oversized input.

Technical Details

Vulnerable Function Behavior

  • The pincode parameter is read directly from an HTTP POST request.
  • The value is written into a 132-byte stack buffer using sprintf().
  • No bounds checking or input validation is performed.
  • Any input longer than 132 bytes will overflow the stack buffer.

Why This Is Dangerous

Stack-based buffer overflows can:

  • Overwrite saved frame pointers and return addresses
  • Crash the web server process
  • Potentially allow attackers to redirect program execution

On embedded systems like routers—where protections such as ASLR, stack canaries, and DEP are often limited or absent—this type of vulnerability is especially dangerous.

How This Vulnerability Can Be Exploited

Attack Scenario

  1. An attacker identifies a KuWFi AC900 router exposed to the internet or reachable from the local network.
  2. The attacker sends a crafted HTTP POST request to /goform/formMultiApnSetting.
  3. The pincode parameter contains a payload significantly larger than 132 bytes.
  4. The overflow corrupts adjacent stack memory.
  5. Depending on memory layout and runtime conditions:
    • The web server crashes (Denial of Service), or
    • Execution flow is hijacked, potentially leading to arbitrary code execution.

Practical Impact

  • Denial of Service: The router’s web interface becomes unavailable until reboot.
  • Persistent Disruption: Repeated exploitation can keep the device offline.
  • Potential Full Device Compromise: If exploited successfully, attackers may gain control over the router, allowing traffic interception, configuration changes, or lateral movement inside the network.

Proof-of-Concept (PoC) Status

  • No official public PoC has been released.
  • However, the vulnerability is trivial to reproduce:
    • Any oversized pincode value (e.g., >300 bytes) will reliably crash the service.
  • Given the simplicity of the flaw, weaponized exploits are considered highly likely.

Example Malicious Payload (Conceptual)

POST /goform/formMultiApnSetting HTTP/1.1
Host: router-ip
Content-Type: application/x-www-form-urlencoded
Content-Length: 600

pincode=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

This payload alone is sufficient to trigger memory corruption.

Detection and Monitoring

How This Attack Can Be Detected

Network Indicators

  • HTTP POST requests targeting /goform/formMultiApnSetting
  • Unusually long pincode parameters
  • Repeated failed or abnormal requests to the same endpoint

System Behavior Indicators

  • Sudden restart or crash of the web server process
  • Router becoming unresponsive without configuration changes
  • Unexpected configuration resets

Detection Rules (Conceptual)

Web Application Firewall (WAF)

  • Block or alert on POST requests where:
    • pincode length exceeds expected limits (e.g., >16 characters)
    • Requests target /goform/formMultiApnSetting with abnormal payload sizes

IDS/IPS Signature Logic

  • Match HTTP requests containing:
    • URI: /goform/formMultiApnSetting
    • Parameter: pincode
    • Payload length exceeding 132 bytes

Relevant Log Sources

To effectively detect exploitation attempts, monitor:

  • Router HTTP access logs
  • Embedded web server crash logs
  • System kernel logs (unexpected process termination)
  • Network firewall or gateway logs
  • IDS/IPS alert logs

Routers deployed in enterprise or ISP environments should forward logs to a centralized SIEM for correlation.

MITRE ATT&CK Mapping

  • T1190 – Exploit Public-Facing Application
    Attackers exploit the exposed web management interface.
  • T1068 – Exploitation for Privilege Escalation
    Successful exploitation may allow elevated control over the device.
  • T1499 – Endpoint Denial of Service
    Crashing the embedded web service disrupts availability.

Mitigation and Remediation

Official Patch

KuWFi has released a firmware update addressing this vulnerability by replacing unsafe string handling with bounded functions and adding input validation.

Action Required:
Update the router firmware immediately using the official KuWFi firmware download page:

Additional Security Recommendations

  • Disable remote management access if not required.
  • Restrict router management interfaces to trusted IP addresses.
  • Place the router behind a firewall that blocks external access to admin endpoints.
  • Regularly review firmware versions and apply updates promptly.

Conclusion

CVE-2025-68706 is a classic but highly dangerous stack-based buffer overflow in a widely deployed embedded router. Due to its low attack complexity, lack of authentication requirements, and exposure through the web interface, this vulnerability poses a real risk to both home and enterprise environments. Immediate patching and proper network hardening are strongly advised to prevent service disruption or full device compromise.

Aegiron

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