CVE-2025-11326 Overview
CVE-2025-11326 is a stack-based buffer overflow vulnerability in the Tenda AC18 router running firmware version 15.03.05.19(6318). The flaw resides in the /goform/WifiMacFilterSet endpoint, where the wifi_chkHz argument is processed without sufficient bounds checking. An attacker with network access and low privileges can manipulate this parameter to corrupt stack memory on the device. Public disclosure of the exploit details has occurred through IoT vulnerability research repositories. The weakness is tracked under CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer.
Critical Impact
Remote attackers can trigger memory corruption on affected Tenda AC18 routers, potentially leading to arbitrary code execution or denial of service on the embedded device.
Affected Products
- Tenda AC18 router (hardware)
- Tenda AC18 firmware version 15.03.05.19(6318)
- Deployments exposing the router web management interface to untrusted networks
Discovery Timeline
- 2025-10-06 - CVE-2025-11326 published to NVD
- 2026-02-24 - Last updated in NVD database
Technical Details for CVE-2025-11326
Vulnerability Analysis
The vulnerability affects the WiFi MAC filter configuration handler exposed through the router's goform web interface. When a client submits a request to /goform/WifiMacFilterSet, the handler reads the wifi_chkHz argument from the request body and copies it into a fixed-size stack buffer. Because the handler does not validate the input length, an oversized value writes past the buffer boundary and overwrites adjacent stack data, including saved return addresses. The condition is reachable over the network from any authenticated user with management access to the device. Successful exploitation can yield arbitrary code execution in the context of the web management process, which typically runs with elevated privileges on consumer router firmware.
Root Cause
The root cause is missing input length validation in the WifiMacFilterSet form handler. The function uses an unsafe memory copy routine such as strcpy or sprintf against the attacker-controlled wifi_chkHz parameter into a stack-allocated buffer. This pattern is consistent with prior memory corruption issues identified across the Tenda AC-series goform handlers, where parameters are accepted without length or character class checks. Refer to the GitHub IoT Vulnerability Documentation for parameter-level details.
Attack Vector
The attack is delivered as an HTTP POST request to the router's web administration interface. The attacker must reach the management endpoint and possess low-privilege credentials, then submit a crafted form with an overlong wifi_chkHz value. No user interaction is required. When the web interface is exposed to the WAN or accessible from a compromised LAN host, the attack can be triggered remotely. The vulnerability is described in the VulDB entry #327209.
No verified proof-of-concept code is reproduced here. The vulnerability mechanics are documented in the external references and consist of submitting an oversized wifi_chkHz parameter value to overflow the destination buffer on the stack.
Detection Methods for CVE-2025-11326
Indicators of Compromise
- HTTP POST requests to /goform/WifiMacFilterSet containing abnormally long wifi_chkHz values
- Unexpected reboots or crashes of the Tenda AC18 web management process (httpd)
- New outbound connections originating from the router to unfamiliar hosts
- Configuration changes to MAC filter settings that were not initiated by an administrator
Detection Strategies
- Inspect router HTTP access logs or upstream proxy logs for requests to /goform/WifiMacFilterSet with parameter lengths exceeding typical bounds
- Deploy network IDS signatures that flag oversized POST bodies targeting Tenda goform endpoints
- Monitor for repeated requests to the WiFi MAC filter endpoint from a single source within a short interval
Monitoring Recommendations
- Capture and centralize router syslog output to detect crashes of the management daemon
- Track WAN-side connection attempts to the router management port from non-administrative source addresses
- Alert on firmware integrity changes or unexpected administrator account creation on the device
How to Mitigate CVE-2025-11326
Immediate Actions Required
- Restrict access to the router web management interface so it is reachable only from trusted internal hosts, never from the WAN
- Change default and weak administrator credentials to reduce the pool of attackers able to reach the authenticated handler
- Audit deployed Tenda AC18 devices and inventory those running firmware 15.03.05.19(6318)
- Segment IoT and consumer network devices away from sensitive corporate assets
Patch Information
At the time of publication, no vendor patch is referenced in the NVD entry. Check the Tenda official website for firmware updates addressing the WifiMacFilterSet handler. If no updated firmware is available, treat the device as unpatched and apply compensating controls.
Workarounds
- Disable remote (WAN) management on the Tenda AC18 and require LAN-only administrative access
- Place the router management interface behind a VPN or jump host for any required remote administration
- Replace affected devices with currently supported hardware where vendor patches are not forthcoming
- Apply firewall rules upstream to drop unsolicited traffic to the router's HTTP management port
# Example firewall rule to block WAN access to the router management port
iptables -A INPUT -i <wan_interface> -p tcp --dport 80 -j DROP
iptables -A INPUT -i <wan_interface> -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.
