CVE-2026-15484: TRENDnet TEW-821DAP Buffer Overflow Flaw

CVE-2026-15484 Overview

CVE-2026-15484 is a buffer overflow vulnerability affecting the TRENDnet TEW-821DAP wireless access point running firmware version 1.12B01. The flaw resides in the sub_41EC14 function within the /goform/tools_nslookup endpoint of the Server Side Includes (SSI) component. Attackers can trigger the overflow remotely over the network with low privileges, corrupting memory on the device. TRENDnet has stated the affected device is End of Life (EOL) and declined to confirm or patch the issue. The vulnerability is tracked under [CWE-119] and carries a CVSS v4.0 base score of 8.7.

Critical Impact
Remote attackers with low privileges can trigger memory corruption on affected TRENDnet TEW-821DAP devices, potentially leading to arbitrary code execution or device compromise on unsupported hardware.

Affected Products

TRENDnet TEW-821DAP firmware version 1.12B01
TRENDnet TEW-821DAP v1.0R (End of Life)
SSI component handling /goform/tools_nslookup requests

Discovery Timeline

2026-07-12 - CVE-2026-15484 published to NVD
2026-07-13 - Last updated in NVD database

Technical Details for CVE-2026-15484

Vulnerability Analysis

The vulnerability exists in the sub_41EC14 function inside the SSI (Server Side Includes) handler for the /goform/tools_nslookup web endpoint. This endpoint exposes the device's diagnostic nslookup utility through the administrative web interface. The function processes user-supplied input without enforcing proper bounds on the destination buffer.

When an attacker submits a crafted request with an oversized parameter, the copy operation writes past the allocated buffer boundary. This overwrites adjacent memory regions including stack frames or heap metadata on the embedded device. The attack is reachable across the network and requires only low-level authenticated access to the web interface.

Embedded devices such as the TEW-821DAP typically lack modern exploit mitigations. Absent protections like Address Space Layout Randomization (ASLR) and stack canaries make control-flow hijacking practical once memory corruption is achieved.

Root Cause

The root cause is improper restriction of operations within the bounds of a memory buffer, classified as [CWE-119]. The sub_41EC14 function copies attacker-controlled data from an HTTP request parameter into a fixed-size buffer without validating the input length.

Attack Vector

Exploitation requires network access to the device's web management interface and low-privilege credentials. An attacker sends a specially crafted HTTP request to /goform/tools_nslookup containing an oversized payload targeting the vulnerable parameter. The sub_41EC14 function then processes the input and triggers the overflow. Because the device is EOL, no vendor patch will be released. Technical exploitation details are documented in the TEW-821DAP Buffer Overflow Analysis and the VulDB entry for CVE-2026-15484.

Detection Methods for CVE-2026-15484

Indicators of Compromise

Unexpected HTTP POST requests to /goform/tools_nslookup containing abnormally long parameter values
Unexpected reboots, service crashes, or web interface unavailability on TEW-821DAP devices
Outbound connections from the access point to unfamiliar external hosts following administrative requests

Detection Strategies

Inspect web server and reverse proxy logs for requests to the tools_nslookup endpoint with payload sizes exceeding expected input lengths
Deploy network intrusion detection signatures matching oversized parameters in /goform/tools_nslookup traffic
Correlate device availability metrics with administrative HTTP requests to identify crash-restart patterns

Monitoring Recommendations

Monitor management-plane traffic to legacy TRENDnet devices and alert on anomalous request sizes to SSI endpoints
Track authentication events on the TEW-821DAP web interface and investigate low-privilege accounts issuing diagnostic requests
Enable SNMP or syslog forwarding from network infrastructure to a centralized log platform for behavioral baselining

How to Mitigate CVE-2026-15484

Immediate Actions Required

Retire and replace TRENDnet TEW-821DAP devices, as the vendor has confirmed EOL status and will not issue patches
Restrict access to the device web management interface to a dedicated management VLAN or trusted administrative hosts only
Rotate credentials on the device and remove any unnecessary low-privilege accounts that could reach the vulnerable endpoint
Segment affected access points from sensitive network zones until decommissioned

Patch Information

No patch is available. TRENDnet has publicly stated: "We are unable to confirm the existence of the vulnerabilities for TEW-821DAP (v1.0R) as these items have been EOL." The only supported remediation is device replacement with a currently maintained model. Additional context is available in the VulDB Vulnerability #377791 record.

Workarounds

Disable remote web management and permit administrative access only from an out-of-band management network
Place the device behind a firewall that blocks external access to the HTTP management port
Apply access control lists to restrict which internal hosts can reach /goform/tools_nslookup
Decommission the device on an accelerated schedule given the absence of vendor support

bash

# Example firewall rule restricting management access to a jump host
iptables -A FORWARD -d <TEW-821DAP-IP> -p tcp --dport 80 -s <mgmt-host-IP> -j ACCEPT
iptables -A FORWARD -d <TEW-821DAP-IP> -p tcp --dport 80 -j DROP