CVE-2026-75783: TRENDnet TEW-WLC100P Buffer Overflow Flaw

CVE-2026-75783 Overview

CVE-2026-75783 is a stack-based buffer overflow vulnerability in TRENDnet TEW-WLC100P firmware version 12.07b01. The flaw resides in the /sbin/netifd binary, specifically within the DHCP blobmsg handler component. An adjacent-network attacker can manipulate DHCP message content to overflow a stack buffer inside the wireless LAN controller. The exploit has been publicly disclosed, increasing the risk of opportunistic use against exposed devices.

Critical Impact
A local-network attacker can trigger memory corruption in the network interface daemon of the TEW-WLC100P wireless controller, enabling denial of service and potential arbitrary code execution with device-level privileges.

Affected Products

TRENDnet TEW-WLC100P Wireless LAN Controller
Firmware version 12.07b01
/sbin/netifd DHCP blobmsg handler component

Discovery Timeline

2026-08-18 - CVE-2026-75783 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-75783

Vulnerability Analysis

The vulnerability is a stack-based buffer overflow [CWE-119] in the netifd network interface daemon shipped with TEW-WLC100P firmware 12.07b01. netifd handles DHCP client messages using the blobmsg serialization format from the OpenWrt libubox library. Improper bounds enforcement during parsing of DHCP-derived blobmsg attributes allows an attacker-controlled value to overwrite adjacent stack memory. The exploitation vector is limited to the adjacent network, meaning the attacker must be reachable at Layer 2 or within the same broadcast domain as the controller.

Successful exploitation can crash the daemon, disrupt wireless controller operations, or allow attacker-controlled code execution in the context of the netifd process. Because netifd typically runs with elevated privileges on embedded network devices, the resulting foothold can be used to pivot into the managed wireless infrastructure.

Root Cause

The root cause is insufficient length validation on DHCP-sourced data before it is copied into a fixed-size stack buffer inside the blobmsg handler in /sbin/netifd. When a crafted DHCP message contains an oversized attribute, the parser writes past the buffer boundary and corrupts saved registers and return addresses on the stack.

Attack Vector

An attacker on the same local or adjacent network as the TEW-WLC100P sends a malicious DHCP message. No authentication or user interaction is required. The netifd process ingests the DHCP data through its blobmsg handler and triggers the overflow while parsing the payload. A proof-of-concept script demonstrating the overflow has been published in a public GitHub PoC Script repository. Additional analysis is available at VulDB CVE Details.

No verified exploit code is included in this article. Refer to the linked references for technical reproduction details.

Detection Methods for CVE-2026-75783

Indicators of Compromise

Unexpected crashes, restarts, or watchdog resets of the netifd process on TEW-WLC100P controllers.
DHCP traffic on the management or client VLAN containing oversized options or malformed vendor-specific fields.
Loss of DHCP service for wireless clients coinciding with anomalous DHCP OFFER, REQUEST, or ACK packets from non-authoritative sources.

Detection Strategies

Inspect DHCP packet captures on segments containing the TEW-WLC100P for option lengths that exceed protocol norms or vendor expectations.
Correlate device syslog entries showing netifd termination or segmentation faults with concurrent DHCP activity.
Alert on new or unauthorized DHCP servers or clients appearing in wireless management VLANs.

Monitoring Recommendations

Forward controller syslog to a centralized logging platform and alert on netifd process failures.
Enable DHCP snooping and rogue DHCP detection on switches adjacent to the wireless controller.
Monitor wireless controller availability metrics to detect service disruption caused by exploitation attempts.

How to Mitigate CVE-2026-75783

Immediate Actions Required

Restrict Layer 2 access to the TEW-WLC100P management interface and any VLAN where the controller runs a DHCP client.
Enforce DHCP snooping and port security on switches to block unauthorized DHCP responders on adjacent networks.
Isolate the affected controller from untrusted user segments until a vendor patch is available.

Patch Information

As of the last NVD update on 2026-08-20, no vendor patch is referenced for TEW-WLC100P firmware 12.07b01. Monitor the TRENDnet support portal and VulDB Vulnerability Details for updated firmware releases addressing the netifdblobmsg handler.

Workarounds

Segment the wireless controller into a dedicated management VLAN with strict access control lists limiting DHCP traffic to trusted servers.
Use static IP configuration on the controller where supported to reduce reliance on DHCP-derived input parsed by netifd.
Deploy network intrusion detection signatures for oversized or malformed DHCP options targeting the controller subnet.

bash

# Example: enable DHCP snooping on an upstream Cisco switch to block rogue DHCP
# servers on the VLAN hosting the TEW-WLC100P
configure terminal
ip dhcp snooping
ip dhcp snooping vlan 10
interface GigabitEthernet0/1
 ip dhcp snooping trust
interface range GigabitEthernet0/2 - 24
 no ip dhcp snooping trust
 ip dhcp snooping limit rate 10
end