CVE-2026-93738 in A3002MU
Summary
by MITRE • 09/18/2026
A vulnerability was found in Totolink A3002MU Hh-B20211125.1046. This affects the function formSchedule of the file /boafrm/formSchedule. Performing a manipulation of the argument webpage results in buffer overflow. The attack is possible to be carried out remotely. The exploit has been made public and could be used.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified in Totolink A3002MU firmware version Hh-B20211125.1046 represents a critical security flaw within the device's web management interface, specifically targeting the formSchedule function located in the /boafrm/formSchedule file. This component is responsible for handling scheduled tasks and configuration settings via the embedded Boa HTTP server commonly found in consumer-grade networking equipment. The core technical issue stems from improper bounds checking when processing user-supplied input passed through the webpage argument. When an attacker provides a specially crafted, excessively long string as part of this argument, it exceeds the allocated buffer size on the stack or heap, leading to a classic buffer overflow condition. This type of memory corruption allows for arbitrary code execution by overwriting adjacent memory locations, including return addresses and function pointers, which can be manipulated to redirect program flow to shellcode injected into the vulnerable process.
From an operational perspective, this vulnerability is particularly dangerous because it can be exploited remotely without requiring any form of authentication or prior access to the network infrastructure. The attack vector leverages the exposed web interface, allowing a threat actor located anywhere on the internet to interact with the device directly over standard HTTP protocols. Since the exploit has been made public, automated scanning tools and malicious actors can readily utilize this proof-of-concept code to compromise vulnerable devices at scale. Successful exploitation typically results in full system takeover, enabling the attacker to execute arbitrary commands with the privileges of the web server process, which often runs as root on embedded Linux systems. This level of access facilitates a wide range of malicious activities, including installing persistent backdoors, pivoting into internal networks for lateral movement, launching distributed denial-of-service attacks using compromised devices as botnet nodes, or exfiltrating sensitive network configuration data and user credentials stored within the device's memory or flash storage.
The technical classification of this flaw aligns with Common Weakness Enumeration (CWE) ID 120, which describes Buffer Copy without Checking Size of Input, a subset of CWE-787 that involves out-of-bounds write operations. In terms of adversary tactics and techniques, the exploitation phase corresponds to MITRE ATT&CK technique T1190, Exploit Public-Facing Application, where attackers leverage known vulnerabilities in internet-facing services to gain initial access. Furthermore, if the attacker utilizes this foothold to maintain persistent control or execute commands remotely, it maps to T1059 Command and Scripting Interpreter and potentially T1505 Server Software Component for persistence mechanisms depending on how the payload is deployed within the embedded environment. The lack of input validation in legacy firmware components like Boa form handlers highlights a systemic issue in many IoT devices where security testing during development phases was insufficient or absent entirely.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary defense involves applying vendor-provided firmware updates that patch the buffer overflow by implementing strict length checks on all incoming arguments before they are processed by the formSchedule function. Organizations relying on these devices should ensure their inventory is up to date with the latest security patches released by Totolink for this specific model and build number. In scenarios where immediate patching is not feasible, network-level controls can provide temporary relief; deploying firewall rules or access control lists to restrict HTTP traffic from untrusted networks to the management IP address of the device significantly reduces the attack surface. Additionally, disabling remote administration features if they are not strictly necessary eliminates the external exposure vector entirely. For environments with high security requirements, segmenting IoT devices into isolated VLANs prevents lateral movement in case a compromise does occur, thereby containing the blast radius and protecting critical internal assets from being leveraged as part of an attack chain originating from this vulnerable endpoint.