CVE-2023-43135 in ER5120G
Summary
by MITRE • 09/21/2023
There is an unauthorized access vulnerability in TP-LINK ER5120G 4.0 2.0.0 Build 210817 Rel.80868n, which allows attackers to obtain sensitive information of the device without authentication, obtain user tokens, and ultimately log in to the device backend management.
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Analysis
by VulDB Data Team • 02/03/2026
The CVE-2023-43135 vulnerability represents a critical unauthorized access flaw in TP-LINK ER5120G 4.0 2.0.0 firmware version, specifically affecting the 2.0.0 Build 210817 Rel.80868n release. This vulnerability resides within the device's authentication mechanisms and represents a significant security weakness that undermines the fundamental principle of access control. The flaw allows remote attackers to bypass authentication procedures entirely, gaining access to sensitive device information and user tokens without requiring legitimate credentials. This type of vulnerability directly violates the security principle of least privilege and demonstrates a failure in implementing proper access validation controls.
The technical implementation of this vulnerability appears to stem from insufficient input validation and authentication checks within the device's web interface management system. Attackers can exploit this weakness to perform unauthorized access operations that typically require valid authentication credentials. The vulnerability enables the extraction of sensitive information including but not limited to device configuration details, user session tokens, and potentially administrative credentials. This flaw operates at the application layer and affects the device's web management interface, which is commonly used for network administration and configuration tasks. The vulnerability aligns with CWE-287 which addresses improper authentication issues, specifically focusing on the absence of proper authentication mechanisms that allow unauthorized access to protected resources.
The operational impact of CVE-2023-43135 extends beyond simple information disclosure, as it provides attackers with the capability to achieve full administrative access to the network device. Once exploited, attackers can manipulate network configurations, modify firewall rules, access network traffic, and potentially use the compromised device as a pivot point for further attacks within the network infrastructure. The vulnerability creates an attack surface that can be leveraged for persistent access and lateral movement, making it particularly dangerous in enterprise environments where network devices serve as critical infrastructure components. This weakness directly enables the execution of attacks categorized under the ATT&CK framework's privilege escalation and persistence tactics, as attackers can establish long-term access to the network management system.
Mitigation strategies for this vulnerability should include immediate firmware updates from TP-LINK to address the authentication bypass flaw, followed by network segmentation to limit access to administrative interfaces. Network administrators should implement strict access controls restricting management interface access to authorized personnel only and deploy network monitoring solutions to detect suspicious access patterns. Additional protective measures include enabling multi-factor authentication where available, implementing strong network access control lists, and conducting regular security assessments of network infrastructure devices. The vulnerability highlights the importance of maintaining up-to-date firmware and implementing robust security practices for network equipment, as outlined in NIST SP 800-121 and other cybersecurity frameworks that emphasize the need for continuous monitoring and timely patch management. Organizations should also consider implementing network behavior analysis tools to detect anomalous access patterns that may indicate exploitation of similar authentication bypass vulnerabilities.