CVE-2025-3802 Overview
CVE-2025-3802 is a stack-based buffer overflow [CWE-119] affecting Tenda W12 and i24 wireless access points running firmware versions 3.0.0.4(2887) and 3.0.0.5(3644). The flaw resides in the cgiPingSet function within the /bin/httpd binary. Attackers can trigger the overflow by manipulating the pingIP argument supplied to the web interface. The vulnerability is remotely exploitable over the network and requires only low-level privileges. Public disclosure of the exploit has occurred through the GitHub Issue Tracker, increasing the likelihood of opportunistic exploitation against exposed devices.
Critical Impact
Remote attackers with low privileges can corrupt stack memory in the httpd process, enabling arbitrary code execution and full compromise of affected Tenda 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 above firmware versions
Discovery Timeline
- 2025-04-19 - CVE-2025-3802 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3802
Vulnerability Analysis
The vulnerability exists in the HTTP daemon (/bin/httpd) that exposes the device's web administration interface. The cgiPingSet handler processes a user-supplied pingIP parameter intended to specify a target address for a diagnostic ping operation. The function copies this input into a fixed-size stack buffer without validating its length, causing memory beyond the buffer boundary to be overwritten when oversized input is supplied.
Because the overflow occurs on the stack, attackers can overwrite saved return addresses and adjacent control data. Successful exploitation grants code execution in the context of the httpd process, which typically runs with elevated privileges on embedded routers. The EPSS score of 0.828% reflects current modeled exploitation likelihood for internet-facing instances.
Root Cause
The root cause is the absence of bounds checking on the pingIP parameter before it is copied into a fixed-size local buffer. The cgiPingSet function trusts the length of attacker-controlled HTTP input, violating safe string-handling practices for embedded C code. This pattern is consistent with [CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer].
Attack Vector
The attack is network-based and targets the HTTP management interface of the access point. An authenticated user with low-privilege credentials sends a crafted HTTP request to the ping diagnostic endpoint. The request includes a pingIP value that exceeds the destination buffer size on the stack. When cgiPingSet processes the request, the saved return address is overwritten, redirecting execution to attacker-controlled memory. Devices exposed to the internet or to untrusted internal networks are at highest risk.
No verified proof-of-concept code is published in the references. Technical reporting is available through the GitHub Issue Tracker and VulDB entry #305656.
Detection Methods for CVE-2025-3802
Indicators of Compromise
- HTTP POST or GET requests to the cgiPingSet endpoint on /bin/httpd containing abnormally long pingIP parameter values
- Unexpected reboots, httpd process crashes, or watchdog resets on Tenda W12 and i24 appliances
- Outbound connections from the access point management interface to unfamiliar external hosts
Detection Strategies
- Inspect web traffic destined for Tenda management interfaces for pingIP values exceeding plausible IP address lengths (greater than 45 characters)
- Deploy network IDS signatures that match oversized parameter content targeting cgi-prefixed handler paths on Tenda devices
- Correlate authentication events with subsequent diagnostic endpoint requests to identify suspicious low-privilege sessions
Monitoring Recommendations
- Log all HTTP requests reaching the access point administration interface and forward them to a centralized SIEM
- Monitor for repeated httpd crashes or service restarts that may indicate exploitation attempts
- Track configuration changes and new administrative sessions on Tenda W12 and i24 devices
How to Mitigate CVE-2025-3802
Immediate Actions Required
- Restrict access to the Tenda web management interface to trusted management VLANs and remove any internet exposure
- Rotate administrative credentials and disable unused accounts on affected W12 and i24 devices
- Audit firmware versions across the fleet and isolate any device running 3.0.0.4(2887) or 3.0.0.5(3644)
- Apply vendor firmware updates as soon as Tenda publishes a patched release
Patch Information
No vendor patch is referenced in the published advisory at the time of writing. Customers should monitor the Tenda Website for firmware updates addressing CVE-2025-3802 and apply them through the standard device upgrade workflow.
Workarounds
- Disable remote (WAN-side) HTTP administration on affected access points
- Place Tenda W12 and i24 devices behind a network firewall that blocks inbound HTTP and HTTPS to the management interface from untrusted networks
- Enforce ACLs limiting which client IP addresses may reach the device administration ports
- Replace shared or default administrative credentials with strong, unique passwords to reduce the likelihood of low-privilege access required for exploitation
# Example: block external access to Tenda management interface at the upstream firewall
iptables -A FORWARD -p tcp -d <tenda_device_ip> --dport 80 -m iprange ! --src-range 10.0.0.0-10.0.0.255 -j DROP
iptables -A FORWARD -p tcp -d <tenda_device_ip> --dport 443 -m iprange ! --src-range 10.0.0.0-10.0.0.255 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
