CVE-2023-36947 in X5000R
Summary
by MITRE • 10/25/2023
TOTOLINK X5000R V9.1.0u.6118_B20201102 and TOTOLINK A7000R V9.1.0u.6115_B20201022 was discovered to contain a stack overflow via the File parameter in the function UploadCustomModule.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 01/15/2026
The vulnerability identified as CVE-2023-36947 affects TOTOLINK X5000R and A7000R router models running specific firmware versions, representing a critical stack overflow condition that could enable remote code execution. This flaw exists within the UploadCustomModule function where the File parameter is processed without adequate input validation, creating a pathway for malicious actors to manipulate the device's memory structure. The stack overflow occurs when an attacker supplies a specially crafted file name or content that exceeds the allocated buffer space, causing the program to overwrite adjacent memory locations and potentially execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability stems from improper bounds checking within the firmware's upload handling mechanism. When the UploadCustomModule function processes the File parameter, it fails to validate the length or content of the uploaded file name, allowing an attacker to overflow the stack buffer and overwrite return addresses or other critical memory segments. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a high-severity issue in the Common Weakness Enumeration catalog due to its potential for remote code execution and privilege escalation. The vulnerability demonstrates poor input sanitization practices that violate fundamental security principles outlined in the OWASP Top Ten and the SANS Institute's most critical web application security risks.
The operational impact of this vulnerability extends beyond simple denial of service, as it could allow attackers to gain unauthorized administrative access to the affected routers. Once exploited, the attacker could modify network configurations, redirect traffic, install malicious firmware, or establish persistent backdoors within the network infrastructure. This poses significant risks to both individual users and enterprise networks, as routers serve as critical gateway devices that control network traffic flow and security policies. The vulnerability affects devices that may be deployed in residential, commercial, or industrial environments, making it particularly concerning given the widespread use of TOTOLINK routers in various network configurations. Attackers could leverage this vulnerability through remote exploitation without requiring physical access or authentication credentials, aligning with the ATT&CK framework's technique T1219 for exploitation of remote services.
Mitigation strategies for CVE-2023-36947 should prioritize immediate firmware updates from TOTOLINK, as the vendor has likely released patches addressing this specific stack overflow condition. Network administrators should also implement network segmentation and access controls to limit potential attack surface, while monitoring for unusual network traffic patterns that might indicate exploitation attempts. Additional defensive measures include disabling unnecessary services, implementing intrusion detection systems, and conducting regular security assessments of network infrastructure. Organizations should consider deploying network-based firewalls to block unauthorized access to router management interfaces and establish secure remote access protocols. The vulnerability highlights the importance of firmware security testing and regular security updates, as well as the need for manufacturers to implement proper input validation and memory management practices to prevent similar stack overflow conditions in future releases.