CVE-2024-3881: Tenda W30E Firmware Buffer Overflow Vulnerability

CVE-2024-3881 Overview

CVE-2024-3881 is a stack-based buffer overflow vulnerability in the Tenda W30E router firmware version 1.0.1.25(633). The flaw resides in the frmL7PlotForm function within the /goform/frmL7ProtForm endpoint. An authenticated remote attacker can manipulate the page argument to overflow a fixed-size stack buffer. Successful exploitation can corrupt saved return addresses and lead to arbitrary code execution on the device. The exploit has been publicly disclosed and the vendor did not respond to disclosure attempts, leaving affected devices without an official fix.

Critical Impact
Remote authenticated attackers can trigger a stack overflow in the router's web management interface to execute arbitrary code and fully compromise the device.

Affected Products

Tenda W30E router hardware
Tenda W30E firmware version 1.0.1.25(633)
Web management endpoint /goform/frmL7ProtForm

Discovery Timeline

2024-04-16 - CVE-2024-3881 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-3881

Vulnerability Analysis

The vulnerability is a classic stack-based buffer overflow [CWE-121] combined with an out-of-bounds write [CWE-787]. The frmL7PlotForm handler processes HTTP requests submitted to /goform/frmL7ProtForm on the router's web administration interface. When the handler parses the page request parameter, it copies the attacker-controlled value into a fixed-size stack buffer without validating the input length.

Because the destination buffer is allocated on the stack, oversized input overwrites adjacent stack data, including the saved return address of the calling function. On MIPS-based Tenda devices, controlling the return address commonly leads to arbitrary code execution through return-oriented programming against the busybox and shared library address space.

The attack requires low-privileged authenticated access to the router's web interface. Because the router exposes the same interface to the local network, any user with valid credentials on the LAN can trigger the flaw. The EPSS model rates the probability of exploitation at 1.459% (71st percentile), reflecting the availability of public technical details.

Root Cause

The root cause is the absence of bounds checking on the page HTTP parameter inside frmL7PlotForm. The function uses an unsafe string copy primitive (such as strcpy or sprintf) to move the parameter into a stack buffer of insufficient size. No length validation, canary, or safe-copy wrapper protects the buffer.

Attack Vector

An attacker sends a crafted HTTP POST or GET request to /goform/frmL7ProtForm on the router's management interface. The request includes an oversized page parameter designed to overwrite the return address on the stack. Because MIPS binaries in Tenda firmware are typically compiled without stack canaries or full ASLR, the attacker can reliably redirect execution to shellcode or ROP gadgets. The result is arbitrary code execution in the context of the router's web daemon, which usually runs as root.

No verified exploit code is reproduced here. Technical details are available in the public GitHub IoT Vulnerability Report and the VulDB entry #260915.

Detection Methods for CVE-2024-3881

Indicators of Compromise

HTTP requests to /goform/frmL7ProtForm containing an unusually long page parameter, particularly values exceeding a few hundred bytes.
Web daemon crashes, reboots, or watchdog resets on the Tenda W30E shortly after receiving management-interface traffic.
Unexpected outbound connections from the router to attacker-controlled infrastructure following administrative access.
New or unauthorized configuration changes to firewall, DNS, or routing rules after suspicious HTTP activity.

Detection Strategies

Inspect network traffic to the router's management interface for POST or GET requests to /goform/frmL7ProtForm with anomalous parameter lengths.
Deploy IDS/IPS signatures that flag HTTP requests to Tenda goform endpoints containing binary or non-printable characters in the page field.
Correlate router syslog messages indicating process restarts of the httpd or web management daemon with recent inbound HTTP requests.

Monitoring Recommendations

Forward router logs and NetFlow data to a central log platform and alert on repeated crashes of the management daemon.
Monitor DNS and outbound connections from the router itself. Consumer routers rarely initiate outbound traffic outside of NTP and DDNS.
Track authentication events on the router web UI and alert on brute-force attempts against low-privileged accounts that could gate the exploit.

How to Mitigate CVE-2024-3881

Immediate Actions Required

Restrict access to the Tenda W30E web management interface to trusted management VLANs or specific administrator hosts.
Disable remote (WAN-side) administration on the device to eliminate internet-exposed attack surface.
Rotate all administrative credentials and remove unused low-privileged accounts that could be leveraged to reach the vulnerable endpoint.
Consider replacing the device if it is deployed in a security-sensitive segment, since no vendor patch is available.

Patch Information

No official patch is available. According to the disclosure, the vendor was contacted but did not respond. Organizations operating Tenda W30E devices on firmware 1.0.1.25(633) should monitor the Tenda support portal for future firmware updates and plan migration to a supported platform. Additional technical detail is tracked in VulDB CTI #260915.

Workarounds

Place the router behind an upstream firewall that filters HTTP requests to /goform/frmL7ProtForm from untrusted sources.
Segment the router's management interface onto a dedicated administrative network reachable only via VPN.
Enforce strong, unique credentials on the router to raise the bar for the authenticated precondition required by the exploit.
Where feasible, replace the Tenda W30E with a vendor-supported device that receives active security updates.