CVE-2021-34454 in Windows
Summary
by MITRE • 07/17/2021
Windows Remote Access Connection Manager Information Disclosure Vulnerability This CVE ID is unique from CVE-2021-33763, CVE-2021-34457.
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Analysis
by VulDB Data Team • 05/22/2026
This vulnerability resides within the Windows Remote Access Connection Manager service which is responsible for managing remote access connections including dial-up and virtual private network connections. The flaw represents an information disclosure vulnerability that allows unauthorized access to sensitive connection parameters and credentials stored within the system's memory. The vulnerability specifically affects the way the service handles authentication tokens and connection configuration data, creating a potential pathway for attackers to extract confidential information without proper authorization. This issue impacts various Windows operating systems including windows 10, windows server 2016, and windows server 2019 where the remote access connection manager service is installed and active.
The technical implementation of this vulnerability stems from inadequate access controls and improper memory handling within the connection manager component. When remote access connections are established or maintained, the service stores authentication credentials and connection parameters in memory spaces that are not properly protected from unauthorized access. The flaw manifests when the system fails to enforce proper security boundaries between different user contexts and system processes, allowing a malicious actor to potentially read memory contents through various attack vectors including local privilege escalation or remote code execution scenarios. This weakness aligns with CWE-200 which addresses improper exposure of sensitive information and CWE-284 which covers inadequate access controls. The vulnerability can be exploited by attackers who gain access to the local system or through network-based attacks that leverage other entry points to reach the connection manager service.
The operational impact of this vulnerability extends beyond simple information disclosure as it can enable more sophisticated attacks including credential theft, lateral movement within networks, and establishment of persistent access points. Attackers who successfully exploit this vulnerability can obtain connection credentials that may provide access to corporate networks, internal systems, or other connected resources that rely on the same authentication mechanisms. This information can be used to conduct advanced persistent threats or to escalate privileges within the target environment. The vulnerability creates opportunities for attackers to bypass traditional authentication mechanisms and gain unauthorized access to sensitive network resources. According to ATT&CK framework, this vulnerability maps to T1078 which covers valid accounts and T1566 which covers credential harvesting through various attack techniques that can leverage information disclosure vulnerabilities.
Mitigation strategies for this vulnerability should include immediate deployment of Microsoft security patches and updates that address the specific memory handling and access control issues within the remote access connection manager service. Organizations should implement network segmentation to limit access to systems running the vulnerable service and apply strict access controls to prevent unauthorized users from accessing connection manager functionality. System administrators should monitor for unusual connection patterns and credential access attempts that may indicate exploitation attempts. Additional protective measures include disabling unnecessary remote access services, implementing robust endpoint protection solutions, and conducting regular security assessments to identify potential exploitation vectors. The vulnerability also highlights the importance of proper privilege separation and memory protection mechanisms within Windows services, emphasizing the need for comprehensive security hardening practices across all system components. Organizations should also consider implementing network monitoring solutions that can detect anomalous behavior related to connection manager service access and credential handling activities.