CVE-2025-7586 Overview
CVE-2025-7586 is a stack-based buffer overflow in the Tenda AC500 router running firmware version 2.0.1.9(1307). The flaw resides in the formSetAPCfg function exposed through the /goform/setWtpData HTTP endpoint. Attackers can manipulate the radio_2g_1 parameter to corrupt the stack and trigger memory corruption [CWE-787, CWE-119]. The issue is remotely reachable over the network and a public proof-of-concept has been disclosed, increasing exposure for unpatched devices.
Critical Impact
Remote attackers with low privileges can corrupt stack memory on Tenda AC500 devices, enabling denial of service and potential arbitrary code execution on the router.
Affected Products
- Tenda AC500 router (hardware)
- Tenda AC500 firmware version 2.0.1.9(1307)
- Deployments exposing the /goform/setWtpData web management endpoint
Discovery Timeline
- 2025-07-14 - CVE-2025-7586 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-7586
Vulnerability Analysis
The vulnerability exists in the formSetAPCfg handler inside the Tenda AC500 web management binary (httpd). The handler processes the /goform/setWtpData request used to configure wireless access point parameters. When the request parses the radio_2g_1 argument, the function copies attacker-controlled data into a fixed-size stack buffer without enforcing length checks. The result is a classic stack-based buffer overflow that overwrites adjacent stack memory, including saved return addresses and frame pointers.
Successful exploitation produces immediate process termination at minimum and may allow arbitrary code execution on the MIPS-based router. Because the router operates with elevated privileges and routes traffic for connected clients, code execution grants full control of network egress, DNS resolution, and management interfaces.
Root Cause
The root cause is missing bounds validation on the radio_2g_1 request parameter before it is copied into a local stack buffer inside formSetAPCfg. The function relies on unsafe string handling rather than length-checked copies, which violates secure coding practices for boundary enforcement.
Attack Vector
The attack is delivered over the network through an HTTP POST request to /goform/setWtpData. The attacker submits an oversized value in the radio_2g_1 field to overflow the destination buffer. The CVSS vector indicates the attacker requires low privileges, suggesting authenticated access to the management interface. Devices exposing the administrative interface to untrusted networks face the highest risk.
Technical details and the proof-of-concept request structure are documented in the GitHub PoC writeup and the VulDB entry #316285.
Detection Methods for CVE-2025-7586
Indicators of Compromise
- HTTP POST requests to /goform/setWtpData containing unusually long radio_2g_1 parameter values.
- Unexpected reboots, httpd crashes, or watchdog resets logged on the AC500 device.
- Configuration changes to access point settings that do not correlate with authorized administrator activity.
Detection Strategies
- Inspect web server access logs on the device or upstream proxy for POST bodies exceeding expected lengths for AP configuration fields.
- Deploy network IDS signatures that match /goform/setWtpData requests with radio_2g_1 payloads above a defined byte threshold.
- Correlate management-plane HTTP requests with source IPs outside the administrative VLAN to surface unauthorized access attempts.
Monitoring Recommendations
- Forward router syslog and HTTP access logs to a centralized log platform for retention and search.
- Alert on repeated authentication failures against the AC500 web UI followed by successful logins from the same source.
- Track outbound connections from the router itself to detect post-exploitation command-and-control activity.
How to Mitigate CVE-2025-7586
Immediate Actions Required
- Restrict access to the AC500 web management interface to trusted administrative networks using ACLs or firewall rules.
- Disable remote (WAN-side) management on the AC500 if it is currently enabled.
- Rotate administrative credentials and enforce strong, unique passwords to reduce the chance of low-privilege access being abused.
- Monitor the Tenda official website for firmware updates addressing this issue.
Patch Information
At the time of NVD publication, Tenda had not released a firmware update fixing CVE-2025-7586 for AC500 firmware 2.0.1.9(1307). Administrators should track vendor advisories on the Tenda official website and apply patched firmware as soon as it becomes available. Until a fix ships, treat the device as exposed and apply compensating controls.
Workarounds
- Place the AC500 management interface behind a VPN or jump host so that /goform/setWtpData is unreachable from untrusted networks.
- Segment the router management VLAN from user and guest networks to limit lateral access to the web UI.
- Where possible, replace or decommission AC500 devices that must be exposed to untrusted networks until a vendor patch is released.
# Example iptables rule restricting AC500 web UI to a management subnet
# Run on an upstream firewall, replacing the placeholders
iptables -A FORWARD -p tcp -d <AC500_IP> --dport 80 -s 10.10.0.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <AC500_IP> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <AC500_IP> --dport 443 -s 10.10.0.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <AC500_IP> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
