CVE-2026-10121: TRENDnet TEW-432BRP formSetUrlFilter stack-based overflow

Synopsis

A stack-based buffer overflow in the formSetUrlFilter handler of TRENDnet's TEW-432BRP router (firmware 3.10B20) lets an authenticated attacker corrupt memory by sending oversized keyword_list or keyword values to /goform/formSetUrlFilter. The bug is reachable over the network and requires only a low-privilege account, and successful exploitation gives full read, write, and availability impact on the device, typically leading to code execution or a device crash. The product has been end-of-life since 2009 and the vendor will not ship a fix; HarborGuard tracks the advisory and will surface a patched rebuild if one is ever published.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the router's HTTP management interface over the network (AV:N).

• AuthenticationRequired

  A low-privilege account on the device is sufficient to invoke the vulnerable handler (PR:L).

• Victim interactionNot required

  No user has to click or open anything; the attacker drives the request directly (UI:N).

• Attack complexityDetail

  Attack complexity is low and a public exploit exists, so the overflow triggers reliably without race conditions or special timing (AC:L).

Blast Radius

• Overwrites the stack of the web management process, typically enabling arbitrary code execution on the router as the web service user.
• Reads any configuration or credential material held in device memory, including admin passwords and VPN secrets.
• Modifies persisted router settings such as firewall, DNS, and URL filtering rules, allowing traffic redirection or interception of LAN clients.
• Crashes the management daemon or the device itself, disrupting connectivity for everyone behind the router.