CVE-2021-21886 in PremierWave
Summary
by MITRE • 12/22/2021
A directory traversal vulnerability exists in the Web Manager FSBrowsePage functionality of Lantronix PremierWave 2050 8.9.0.0R4. A specially crafted HTTP request can lead to information disclosure. An attacker can make an authenticated HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/26/2021
The CVE-2021-21886 vulnerability represents a critical directory traversal flaw within the Lantronix PremierWave 2050 device firmware version 8.9.0.0R4. This vulnerability specifically affects the Web Manager FSBrowsePage functionality, which serves as the file system browsing interface for administrators to navigate and manage device files through the web-based administration portal. The flaw stems from inadequate input validation and sanitization within the file path handling mechanism, allowing malicious actors to manipulate directory traversal sequences and access restricted system files. The vulnerability operates at the application layer and specifically targets the web management interface, making it particularly dangerous as it can be exploited by authenticated users who have legitimate access to the device's administrative functions.
The technical exploitation of this vulnerability involves crafting specially formatted HTTP requests that manipulate the file system browsing parameters to traverse directories beyond the intended scope. When an authenticated user submits a request containing malicious path traversal sequences such as ../ or ..\, the web manager fails to properly validate these inputs, allowing the system to interpret and resolve these paths relative to the root file system. This results in unauthorized access to sensitive files including configuration data, system logs, and potentially credential files that should remain protected within the device's secure file system boundaries. The vulnerability manifests as information disclosure, where attackers can retrieve system files that contain sensitive operational data, potentially including user credentials, network configuration details, and other confidential information that could be leveraged for further attacks.
The operational impact of CVE-2021-21886 extends beyond simple information disclosure, as it creates a pathway for more sophisticated attacks within network environments. An attacker who successfully exploits this vulnerability can gain access to critical system information that could reveal network topology, device configurations, and potentially administrative credentials. This information can be used to conduct advanced persistent threats or to plan more targeted attacks against other systems within the same network infrastructure. The vulnerability particularly affects industrial control systems and network infrastructure devices where the PremierWave 2050 serves as a critical component, making it a significant concern for organizations operating in sectors such as manufacturing, utilities, and critical infrastructure where network security is paramount. The authenticated nature of the exploit means that the vulnerability requires legitimate access credentials, but once exploited, it provides access to sensitive operational data that could compromise the entire network security posture.
Organizations should implement immediate mitigations including firmware updates from Lantronix to address the directory traversal vulnerability, along with network segmentation to limit access to administrative interfaces. Access controls should be strictly enforced through role-based permissions and multi-factor authentication to reduce the risk of unauthorized access. Network monitoring should be enhanced to detect anomalous file system access patterns that could indicate exploitation attempts. The vulnerability aligns with CWE-22 directory traversal weakness and can be mapped to ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing) where attackers may use the disclosed information for further social engineering attacks. Regular security assessments of industrial control systems should include verification of firmware versions and patch management processes to prevent similar vulnerabilities from persisting in operational environments.