CVE-2025-3803 Overview
CVE-2025-3803 is a stack-based buffer overflow vulnerability in 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 cgiSysScheduleRebootSet function within the /bin/httpd binary. Attackers can trigger the overflow by manipulating the rebootDate argument supplied to the web management interface. The exploit has been publicly disclosed, increasing the likelihood of opportunistic attacks against exposed devices. The vulnerability is classified under [CWE-119], improper restriction of operations within memory buffer bounds.
Critical Impact
Remote attackers with low privileges can corrupt the stack of the embedded HTTP server, enabling arbitrary code execution or denial of service against affected Tenda W12 and i24 wireless access points.
Affected Products
- Tenda W12 firmware 3.0.0.4(2887) and 3.0.0.5(3644)
- Tenda i24 firmware 3.0.0.4(2887) and 3.0.0.5(3644)
- Tenda W12 and i24 hardware appliances running the affected firmware builds
Discovery Timeline
- 2025-04-19 - CVE-2025-3803 published to the National Vulnerability Database
- 2025-07-30 - Last updated in NVD database
Technical Details for CVE-2025-3803
Vulnerability Analysis
The vulnerability sits in the cgiSysScheduleRebootSet handler exported by the Tenda httpd daemon. This handler processes scheduled-reboot configuration submitted through the device web interface. The handler reads the rebootDate parameter from the request and copies it into a fixed-size stack buffer without enforcing length checks. Supplying an oversized rebootDate value overwrites adjacent stack data, including saved return addresses on the MIPS-based platform used by these access points.
Because httpd runs with elevated privileges on the device, successful exploitation can yield full control of the underlying operating system. Public discussion of the issue includes proof-of-concept details on the GitHub Issue Discussion and the VulDB CTI ID #305657 entry.
Root Cause
The root cause is the absence of bounds validation when the request parameter rebootDate is copied into a local stack buffer inside cgiSysScheduleRebootSet. Embedded web handlers in the Tenda firmware rely on unsafe string operations rather than length-checked variants, allowing user-supplied input to exceed the destination buffer size.
Attack Vector
The attack is initiated remotely over the network against the device management interface. An authenticated low-privilege user can send a crafted HTTP request containing an oversized rebootDate value to the scheduled-reboot endpoint served by /bin/httpd. When the device is reachable from untrusted networks, this exposure increases significantly. Refer to the VulDB #305657 entry for further technical context.
Detection Methods for CVE-2025-3803
Indicators of Compromise
- HTTP POST or GET requests to the device management interface containing unusually long rebootDate parameter values.
- Unexpected httpd process crashes, reboots, or watchdog resets on Tenda W12 or i24 devices.
- Configuration changes to scheduled reboot settings that were not initiated by an administrator.
- New or unknown sessions authenticated to the device web UI from external IP addresses.
Detection Strategies
- Inspect web access logs on the device or upstream proxies for requests targeting the schedule-reboot endpoint with abnormal parameter lengths.
- Monitor network traffic to management VLANs for HTTP requests sourced from non-administrative subnets.
- Compare firmware versions across the fleet to identify devices still running 3.0.0.4(2887) or 3.0.0.5(3644).
Monitoring Recommendations
- Forward Tenda device logs to a centralized SIEM and alert on repeated httpd restarts.
- Apply network IDS signatures that flag oversized parameter values on Tenda management URIs.
- Track outbound connections from access points to unexpected destinations, which may indicate post-exploitation activity.
How to Mitigate CVE-2025-3803
Immediate Actions Required
- Restrict access to the web management interface to trusted administrative networks using firewall ACLs.
- Disable WAN-side management on Tenda W12 and i24 devices if previously enabled.
- Rotate administrative credentials, since the attack requires a low-privileged authenticated session.
- Inventory all Tenda W12 and i24 devices and identify those running the affected firmware versions.
Patch Information
No vendor patch has been published in the references available at the time of CVE assignment. Administrators should monitor the Tenda Official Website for firmware updates addressing CVE-2025-3803 and the related VulDB Submission #554756 record for advisory updates.
Workarounds
- Place affected access points behind a segmented management network reachable only via VPN.
- Block HTTP access to the device management interface from user and guest VLANs.
- Limit the number of administrative accounts and enforce strong, unique passwords to reduce the pool of credentials usable for exploitation.
- Replace end-of-support devices with hardware that receives active firmware maintenance if no patch becomes available.
# Example: restrict Tenda management interface to a trusted subnet using an upstream firewall
# Replace 192.0.2.0/24 with your administrative network and 10.0.0.10 with the device IP
iptables -A FORWARD -s 192.0.2.0/24 -d 10.0.0.10 -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d 10.0.0.10 -p tcp --dport 80 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
