CVE-2025-4007 Overview
CVE-2025-4007 is a stack-based buffer overflow [CWE-119] affecting Tenda W12 and i24 access points running firmware versions 3.0.0.4(2887) and 3.0.0.5(3644). The flaw resides in the cgidhcpsCfgSet function within /goform/modules, a handler exposed by the device's httpd web management component. An authenticated remote attacker can manipulate the json argument to overflow a stack buffer and corrupt adjacent memory. The exploit details have been published, increasing the likelihood of opportunistic attacks against exposed devices. Both the W12 and i24 are enterprise-class wireless access points commonly deployed in hospitality, education, and small business networks.
Critical Impact
Remote attackers with low privileges can corrupt memory in the httpd process, leading to denial of service or potential arbitrary code execution on affected Tenda W12 and i24 devices.
Affected Products
- Tenda W12 firmware 3.0.0.4(2887)
- Tenda W12 firmware 3.0.0.5(3644)
- Tenda i24 firmware 3.0.0.4(2887) and 3.0.0.5(3644)
Discovery Timeline
- 2025-04-28 - CVE-2025-4007 published to NVD
- 2025-07-30 - Last updated in NVD database
Technical Details for CVE-2025-4007
Vulnerability Analysis
The vulnerability resides in the cgidhcpsCfgSet function, which handles DHCP server configuration requests submitted to /goform/modules through the device's embedded httpd daemon. The handler parses a json parameter supplied in the HTTP request body and copies attacker-controlled values into a fixed-size stack buffer without enforcing length validation. Sending an oversized json payload overflows the stack frame and overwrites adjacent control data, including the saved return address.
Because the exploit can be triggered over the network and affects a core configuration endpoint, attackers can target devices reachable from internal networks or, where remote management is enabled, from the internet. Successful exploitation can crash the management interface or, depending on memory layout and protections present on the device, redirect execution to attacker-supplied shellcode.
Root Cause
The root cause is missing bounds checking when the cgidhcpsCfgSet handler deserializes JSON input into a fixed-size stack buffer. The code trusts the length of attacker-supplied fields and performs an unchecked copy, classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer). Embedded SOHO routers frequently lack stack canaries, ASLR, and non-executable stacks, which raises the likelihood that memory corruption is convertible to code execution.
Attack Vector
Exploitation requires the attacker to reach the httpd service over the network and possess valid management credentials. The attacker issues a crafted HTTP POST request to /goform/modules invoking the cgidhcpsCfgSet action with an oversized json argument. Public technical details and a proof-of-concept have been disclosed through the GitHub Issue Report and VulDB CTI ID #306343, lowering the barrier for weaponization.
Detection Methods for CVE-2025-4007
Indicators of Compromise
- HTTP POST requests to /goform/modules with abnormally large json parameter values directed at Tenda W12 or i24 devices.
- Unexpected restarts or crash loops of the httpd process on affected access points.
- Configuration changes to DHCP server settings that do not correspond to legitimate administrative activity.
Detection Strategies
- Inspect HTTP traffic to Tenda management interfaces for requests exceeding expected parameter sizes, particularly the json field on /goform/modules.
- Correlate authentication events on the device web UI with subsequent crashes or configuration changes to surface exploitation attempts.
- Apply IDS/IPS signatures that match oversized JSON payloads targeting cgidhcpsCfgSet.
Monitoring Recommendations
- Forward syslog and crash telemetry from Tenda devices to a centralized log platform for retention and alerting.
- Monitor north-south and east-west traffic for unauthorized access attempts to access point management ports (typically TCP/80 and TCP/443).
- Track firmware versions across the fleet to identify devices still running 3.0.0.4(2887) or 3.0.0.5(3644).
How to Mitigate CVE-2025-4007
Immediate Actions Required
- Restrict access to the httpd management interface so that only trusted administrative VLANs or hosts can reach the device.
- Disable remote (WAN-side) management on all Tenda W12 and i24 devices.
- Rotate administrative credentials, since exploitation requires authenticated access and reused passwords expand the attack surface.
- Audit access point inventories to identify all devices running the affected firmware revisions.
Patch Information
At the time of NVD publication, no vendor patch had been referenced in the advisory. Operators should monitor the Tenda support site for firmware updates addressing the cgidhcpsCfgSet handler and apply them as soon as they are released. Additional disclosure details are tracked in VulDB #306343.
Workarounds
- Place affected access points behind a management firewall and permit web UI access only from a dedicated jump host.
- Enforce strong, unique credentials for the device administrative account to reduce the likelihood that an attacker meets the low-privilege precondition.
- Consider replacing end-of-support hardware with models that receive active security maintenance if a patch is not released in a timely manner.
# Example: restrict Tenda management interface access at an upstream firewall (iptables)
iptables -A FORWARD -p tcp -d <TENDA_AP_IP> --dport 80 -s <MGMT_SUBNET> -j ACCEPT
iptables -A FORWARD -p tcp -d <TENDA_AP_IP> --dport 443 -s <MGMT_SUBNET> -j ACCEPT
iptables -A FORWARD -p tcp -d <TENDA_AP_IP> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <TENDA_AP_IP> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
