CVE-2026-93740 in A3002MU
Summary
by MITRE • 09/19/2026
A vulnerability was identified in Totolink A3002MU Hh-B20211125.1046. Affected is the function formWlEncrypt of the file /boafrm/formWlEncrypt. The manipulation of the argument submit-url leads to buffer overflow. It is possible to initiate the attack remotely. The exploit is publicly available and might be used.
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Analysis
by VulDB Data Team • 09/19/2026
The vulnerability identified in Totolink A3002MU firmware version Hh-B20211125.1046 represents a critical security flaw within the device's web management interface, specifically located in the formWlEncrypt function of the boafrm file. This component is responsible for handling wireless encryption configuration submissions from users via the embedded web server. The core technical issue stems from improper input validation and bounds checking when processing the submit-url argument passed to this function. When an attacker provides a maliciously crafted string that exceeds the expected buffer size, it triggers a classic stack-based or heap-based buffer overflow condition. This memory corruption allows for arbitrary code execution on the target device by overwriting adjacent memory structures, such as return addresses or function pointers, thereby hijacking the control flow of the application.
From an operational perspective, this vulnerability is particularly severe because it can be exploited remotely without requiring any prior authentication. The web server component typically listens on standard HTTP ports and processes incoming requests from any network interface accessible to the attacker. This means that a remote adversary located anywhere with network connectivity to the router's management IP address can initiate the attack vector directly through crafted HTTP POST or GET requests containing the oversized submit-url parameter. The availability of public exploits significantly lowers the barrier to entry for attackers, enabling automated scanning tools and opportunistic threat actors to compromise vulnerable devices at scale. Once exploited, an attacker gains full control over the router's operating system, which can lead to complete network compromise, including interception of traffic, installation of persistent backdoors, or using the device as a pivot point for further attacks against internal networks.
In terms of industry standard classifications, this vulnerability aligns with CWE-120 Buffer Copy without Checking Size of Input and CWE-78 Improper Neutralization of Special Elements used in an OS Command if command injection is also possible through similar mechanisms, though the primary classification remains buffer overflow leading to remote code execution. The attack technique corresponds to MITRE ATT&CK Tactic TA0001 Initial Access with specific techniques such as T1190 Exploit Public-Facing Application and potentially T1203 Exploitation for Client Execution if the payload targets client-side components, although in this embedded context it primarily facilitates persistent access. The lack of authentication requirement places it firmly within high-severity categories according to CVSS scoring guidelines due to its network exploitability and impact on confidentiality, integrity, and availability.
Mitigation strategies must prioritize immediate patching by updating the firmware to a version where formWlEncrypt has been hardened with proper input length validation and safe string handling functions such as strncpy or snprintf instead of unsafe alternatives like strcpy. Network segmentation is recommended to isolate management interfaces from untrusted networks, ensuring that administrative access is only permitted via secure out-of-band connections or VPN tunnels rather than direct internet exposure. Additionally, deploying intrusion detection systems configured to detect buffer overflow patterns in HTTP traffic can provide an additional layer of defense while patches are being applied. Manufacturers should enforce strict input sanitization and implement address space layout randomization if supported by the embedded OS architecture to mitigate exploitation success rates even if similar vulnerabilities exist in other components.