Comprehensive Technical Analysis of CVE-2025-69764

CVE ID: CVE-2025-69764 CVSS Score: 9.8 (Critical) Vulnerability Type: Stack-Based Buffer Overflow (CWE-121) Affected Component: formGetIptv function in Tenda AX3 firmware Affected Version: v16.03.12.11

---

1. Vulnerability Assessment & Severity Evaluation

Technical Root Cause

CVE-2025-69764 is a stack-based buffer overflow vulnerability in the formGetIptv function of Tenda AX3 router firmware. The flaw stems from improper bounds checking when processing the stbpvid parameter, leading to uncontrolled memory corruption.

• Vulnerable Function: formGetIptv
• Exploitable Parameter: stbpvid (stack buffer)
• Overflow Mechanism: The function fails to validate the length of user-supplied input before copying it into a fixed-size stack buffer, allowing an attacker to overwrite adjacent memory structures, including return addresses.

Severity Justification (CVSS 9.8)

CVSS Metric	Score	Rationale
Attack Vector (AV)	Network (N)	Exploitable remotely over the network.
Attack Complexity (AC)	Low (L)	No special conditions required; straightforward exploitation.
Privileges Required (PR)	None (N)	No authentication needed.
User Interaction (UI)	None (N)	Exploitable without user interaction.
Scope (S)	Unchanged (U)	Affects the vulnerable component (router firmware).
Confidentiality (C)	High (H)	Remote code execution (RCE) enables full system compromise.
Integrity (I)	High (H)	Arbitrary code execution allows modification of system behavior.
Availability (A)	High (H)	Crash or persistent denial-of-service (DoS) possible.

Overall CVSS Score: 9.8 (Critical) – This vulnerability is remotely exploitable without authentication, making it a high-priority patching target for organizations and consumers.

---

2. Potential Attack Vectors & Exploitation Methods

Attack Vectors

1. Remote Exploitation via HTTP Requests

   • The formGetIptv function is exposed via the router’s web interface (typically on port 80/443).
   • An attacker can craft a malicious HTTP POST request with an oversized stbpvid parameter to trigger the overflow.

2. LAN-Based Exploitation

   • If the router’s web interface is accessible on the local network, an attacker on the same subnet can exploit the vulnerability without external exposure.

3. WAN-Based Exploitation (If Web Interface is Exposed)

   • If the router’s admin panel is publicly accessible (e.g., misconfigured port forwarding), remote attackers can exploit it over the internet.

Exploitation Steps

1. Reconnaissance

   • Identify vulnerable Tenda AX3 routers via Shodan, Censys, or mass scanning (e.g., http.title:"Tenda AX3").
   • Confirm firmware version (16.03.12.11) via HTTP headers or /goform/getSysTools endpoint.

2. Crafting the Exploit

   • Payload Construction:
     • Overwrite the stack buffer (stbpvid) with shellcode or ROP (Return-Oriented Programming) gadgets.
     • Include a return address overwrite to redirect execution to attacker-controlled memory.
   • Example HTTP Request:

     POST /goform/formGetIptv HTTP/1.1
     Host: <ROUTER_IP>
     Content-Type: application/x-www-form-urlencoded
     Content-Length: <MALICIOUS_LENGTH>
     
     stbpvid=<OVERFLOW_PAYLOAD>&other_param=value
     

   • Shellcode Considerations:
     • MIPS/ARM architecture (depending on router’s CPU).
     • May require ASLR bypass (if enabled) via information leaks or heap spraying.

3. Post-Exploitation

   • Remote Code Execution (RCE):
     • Execute arbitrary commands (e.g., telnetd, wget for malware download).
     • Persist via cron jobs, startup scripts, or firmware modification.
   • Lateral Movement:
     • Pivot into the internal network (e.g., ARP spoofing, DNS hijacking).
   • Botnet Recruitment:
     • Enroll the router in a DDoS botnet (e.g., Mirai, Mozi).

Proof-of-Concept (PoC) Considerations

• A public PoC may emerge shortly after disclosure, increasing exploitation risk.
• Metasploit module likely to be developed, lowering the barrier for script kiddies.

---

3. Affected Systems & Software Versions

Vulnerable Product

• Device: Tenda AX3 (Wi-Fi 6 Router)
• Firmware Version: v16.03.12.11 (confirmed vulnerable)
• Likely Affected Versions:
  • Any prior version with the same formGetIptv implementation.
  • Other Tenda models using similar firmware codebases (e.g., AX12, AX18).

Unaffected Versions

• Patched Firmware: (Not yet released as of Jan 2026)
• Workarounds: See Mitigation Strategies below.

---

4. Recommended Mitigation Strategies

Immediate Actions

Mitigation	Details	Effectiveness
Apply Firmware Update	Wait for Tenda to release a patched version (expected soon).	High (Permanent fix)
Disable Remote Administration	Restrict web interface access to LAN-only (disable WAN access).	Medium (Reduces attack surface)
Network Segmentation	Isolate the router in a DMZ or separate VLAN to limit lateral movement.	Medium (Containment)
Firewall Rules	Block external access to ports 80/443 on the router.	Medium (Prevents WAN exploitation)
Intrusion Detection/Prevention (IDS/IPS)	Deploy Snort/Suricata rules to detect exploitation attempts.	Low-Medium (Detects but does not prevent)

Long-Term Recommendations

1. Vendor Patch Management

   • Monitor Tenda’s official website (www.tenda.com.cn) for firmware updates.
   • Subscribe to CISA alerts and vendor security advisories.

2. Network Hardening

   • Replace default credentials with strong, unique passwords.
   • Disable UPnP and WPS if not required.
   • Enable HTTPS-only administration.

3. Threat Hunting & Monitoring

   • Deploy SIEM solutions (e.g., Splunk, ELK) to detect anomalous HTTP requests.
   • Monitor for unexpected outbound connections from the router.

4. Alternative Firmware (Advanced Users)

   • Consider OpenWRT/DD-WRT if Tenda does not release a timely patch.
   • Risk: Voids warranty; requires technical expertise.

---

5. Impact on the Cybersecurity Landscape

Exploitation Risks

• Mass Exploitation Potential:
  • Tenda routers are widely deployed in SOHO (Small Office/Home Office) environments.
  • Low-hanging fruit for botnet operators (e.g., Mirai variants).
• Supply Chain Risks:
  • ISPs bundling Tenda routers may unknowingly distribute vulnerable devices.
• IoT Security Concerns:
  • Reinforces the need for secure-by-default IoT firmware practices.

Broader Implications

1. Increased Botnet Activity
   • Likely to be weaponized in DDoS campaigns (e.g., targeting gaming, finance, or critical infrastructure).
2. Ransomware & Persistent Threats
   • Attackers may use compromised routers as C2 (Command & Control) proxies.
3. Regulatory & Compliance Impact
   • Organizations using Tenda AX3 may violate NIST SP 800-53, ISO 27001, or GDPR if unpatched.
4. Vendor Reputation Damage
   • Tenda may face customer backlash if patching is delayed, similar to past incidents (e.g., CVE-2020-10987).

---

6. Technical Details for Security Professionals

Vulnerability Deep Dive

Code Analysis (Hypothetical)

The formGetIptv function likely resembles the following (pseudo-C):

void formGetIptv() {
    char stbpvid[64];  // Fixed-size stack buffer
    char *user_input = get_http_param("stbpvid");  // Untrusted input

    strcpy(stbpvid, user_input);  // UNSAFE: No bounds checking
    // ... further processing ...
}

• Vulnerability: strcpy() does not check input length, leading to stack smashing.
• Exploit Primitive: Attacker can overwrite:
  • Return address (for RCE).
  • Stack canaries (if present, may require bypass).
  • Function pointers (e.g., system() calls).

Exploitation Techniques

1. Return-to-libc (Ret2libc)
   • Overwrite return address to call system("/bin/sh").
2. ROP Chains
   • Bypass NX (No-Execute) and ASLR using gadgets from libc.
3. Shellcode Injection
   • Place shellcode in an environment variable or heap memory and jump to it.

Debugging & Reverse Engineering

• Tools for Analysis:
  • Ghidra/IDA Pro (for firmware disassembly).
  • QEMU (for emulating MIPS/ARM firmware).
  • GDB (for dynamic analysis).
• Firmware Extraction:
  • Use binwalk to extract filesystem from firmware binary.
  • Locate formGetIptv in /bin/httpd or /usr/sbin/httpd.

Detection Signatures

• Snort/Suricata Rule:

  alert tcp any any -> $HOME_NET 80 (msg:"Tenda AX3 formGetIptv Buffer Overflow Attempt";
  flow:to_server,established; content:"POST /goform/formGetIptv"; http_method;
  content:"stbpvid="; http_client_body; pcre:"/stbpvid=[^\x00]{100,}/";
  reference:cve,CVE-2025-69764; classtype:attempted-admin; sid:1000001; rev:1;)
  

---

Conclusion & Actionable Recommendations

Key Takeaways

• Critical RCE vulnerability in Tenda AX3 routers with CVSS 9.8.
• Exploitable remotely without authentication, posing a high risk to unpatched devices.
• Likely to be weaponized in botnets, ransomware, and espionage campaigns.

Immediate Actions for Organizations & Consumers

1. Patch Immediately once Tenda releases a fix.
2. Disable WAN access to the router’s admin panel.
3. Monitor network traffic for exploitation attempts.
4. Consider replacing the router if no patch is available in a reasonable timeframe.

For Security Researchers

• Develop PoC exploits for red teaming and penetration testing.
• Contribute to vulnerability databases (e.g., Exploit-DB, MITRE).
• Advocate for secure coding practices in IoT firmware development.

---

References:

• MITRE CVE-2025-69764
• Tenda Security Advisory (Expected)
• CISA Known Exploited Vulnerabilities Catalog