CVE-2025-11524 Overview
CVE-2025-11524 is a stack-based buffer overflow vulnerability in the Tenda AC7 router running firmware version 15.03.06.44. The flaw resides in the /goform/SetDDNSCfg endpoint and is triggered by manipulation of the ddnsEn argument. An attacker can exploit this issue remotely over the network to corrupt stack memory on the device. Public technical documentation of the issue has been released, increasing the risk of opportunistic exploitation against exposed devices. The weakness is classified under CWE-119 for improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low-privileged access can trigger a stack-based buffer overflow in the Tenda AC7 web management interface, potentially leading to arbitrary code execution or denial of service on the router.
Affected Products
- Tenda AC7 router (hardware version 1.0)
- Tenda AC7 firmware version 15.03.06.44
- Deployments exposing the /goform/SetDDNSCfg web management endpoint
Discovery Timeline
- 2025-10-09 - CVE-2025-11524 published to NVD
- 2025-10-09 - Last updated in NVD database
Technical Details for CVE-2025-11524
Vulnerability Analysis
The vulnerability lies in the HTTP handler that processes requests to /goform/SetDDNSCfg on the Tenda AC7 web management interface. The handler reads the ddnsEn request parameter and copies it into a fixed-size stack buffer without enforcing length boundaries. Supplying an oversized value overflows the buffer and corrupts adjacent stack data, including the saved return address. Because the affected binary on consumer routers typically lacks modern exploit mitigations such as stack canaries or address space layout randomization, control-flow hijacking is feasible. Exploitation occurs over the network and requires only low-level access to the web interface. The published technical writeup, IoT-vulnerable repository, documents the affected parameter and request structure.
Root Cause
The root cause is an unsafe string copy operation in the SetDDNSCfg handler. User-supplied data from the ddnsEn parameter is written to a stack buffer without validating input length, matching the [CWE-119] memory boundary violation pattern common in embedded HTTP servers.
Attack Vector
An attacker sends a crafted HTTP POST request to /goform/SetDDNSCfg with an oversized ddnsEn value. The request can be issued from any host able to reach the router's management interface, including the LAN, VPN tunnels, or the WAN if remote administration is enabled. Successful exploitation can crash the device or execute attacker-controlled code in the context of the web server process, which typically runs with elevated privileges on Tenda firmware.
No verified proof-of-concept code is reproduced here. Refer to the GitHub vulnerability documentation and VulDB entry #327662 for detailed reproduction steps.
Detection Methods for CVE-2025-11524
Indicators of Compromise
- HTTP POST requests to /goform/SetDDNSCfg containing abnormally long ddnsEn parameter values
- Unexpected reboots, crashes, or httpd process restarts on the Tenda AC7 router
- Outbound connections from the router to unfamiliar hosts following suspicious DDNS configuration requests
- Configuration changes to dynamic DNS settings that were not initiated by an administrator
Detection Strategies
- Inspect web access logs and network captures for POST requests targeting /goform/SetDDNSCfg with parameter lengths exceeding typical DDNS field sizes
- Deploy intrusion detection signatures that flag oversized form parameters destined for Tenda /goform/* endpoints
- Correlate router availability and reboot events with preceding HTTP traffic to the management interface
Monitoring Recommendations
- Restrict access to the router management interface to a dedicated administrative VLAN and monitor for connections originating elsewhere
- Alert on any WAN-side connection attempts to the router's HTTP/HTTPS management ports
- Track firmware version inventory for Tenda AC7 devices and flag any still running 15.03.06.44
How to Mitigate CVE-2025-11524
Immediate Actions Required
- Disable remote (WAN-side) management on Tenda AC7 devices to limit the attack surface to local network users
- Place affected routers behind upstream filtering that blocks unsolicited HTTP requests to the management interface
- Audit DDNS configuration and reset administrative credentials on devices suspected of exposure
Patch Information
No vendor patch has been published in the referenced advisories at the time of CVE assignment. Monitor the Tenda official website for firmware updates superseding 15.03.06.44. If the AC7 model is end-of-life, plan migration to a supported router with an active security maintenance lifecycle.
Workarounds
- Disable the DDNS feature in the router's web interface to reduce reachability of the vulnerable handler
- Enforce network segmentation so that only trusted administrative hosts can reach the router's management ports
- Replace end-of-support Tenda AC7 hardware with a vendor-supported device that receives security updates
# Example: restrict access to the router management interface using an upstream firewall
# Allow only the administrative host to reach the router's HTTP management port
iptables -A FORWARD -s 192.0.2.10 -d 192.168.0.1 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 192.168.0.1 -p tcp --dport 80 -j DROP
# Block WAN-side access to the management interface
iptables -A INPUT -i eth_wan -p tcp --dport 80 -j DROP
iptables -A INPUT -i eth_wan -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
