CVE-2018-19941 in QTS
Summary
by MITRE • 01/01/2021
A vulnerability has been reported to affect QNAP NAS. If exploited, this vulnerability allows an attacker to access sensitive information stored in cleartext inside cookies via certain widely-available tools. QNAP have already fixed this vulnerability in the following versions: QTS 4.5.1.1456 build 20201015 (and later) QuTS hero h4.5.1.1472 build 20201031 (and later) QuTScloud c4.5.2.1379 build 20200730 (and later)
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Analysis
by VulDB Data Team • 05/21/2026
This vulnerability in QNAP Network Attached Storage systems represents a critical information disclosure flaw that directly impacts the security of user sessions and sensitive data stored within web applications. The vulnerability specifically affects how session cookies are handled within the QNAP operating systems, creating an avenue for attackers to extract sensitive information that should remain protected in encrypted form. The flaw manifests when authentication tokens and session identifiers are transmitted or stored in cleartext format, making them immediately accessible to any attacker with basic reconnaissance capabilities and widely available exploitation tools. This type of vulnerability falls under the category of improper credential handling and weak session management, which are commonly addressed through industry standards such as CWE-312 (Cleartext Storage of Sensitive Information) and CWE-319 (Cleartext Transmission of Sensitive Information).
The technical implementation of this vulnerability stems from the failure to properly encrypt or obfuscate session cookies that contain sensitive authentication data and user privileges within QNAP's web-based administration interfaces. When users authenticate to the QNAP NAS systems through web browsers, the system generates session cookies that should contain encrypted tokens to maintain secure communication between the user and the storage device. However, the flaw allows these cookies to be transmitted or stored in an unencrypted format, enabling attackers to intercept and decode the information contained within them. This creates a persistent security risk where unauthorized parties can gain access to administrative sessions, user credentials, and potentially sensitive data stored on the network attached storage devices. The vulnerability is particularly concerning as it affects the core authentication mechanisms of the system and can be exploited using standard network monitoring and packet analysis tools that are readily available to attackers.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass full administrative access and potential data compromise across affected QNAP NAS installations. An attacker who successfully exploits this vulnerability can establish unauthorized sessions with elevated privileges, potentially gaining access to all files stored on the network attached storage, modifying system configurations, and creating backdoor access points for continued unauthorized access. The affected systems include multiple QNAP operating system variants including QTS 4.5.1.1456 and later, QuTS hero h4.5.1.1472 and later, and QuTScloud c4.5.2.1379 and later, indicating that this was a widespread issue affecting the core web application framework of these systems. The vulnerability creates a significant risk for organizations relying on QNAP NAS devices for critical data storage and management, as it essentially removes the security boundary that should protect against unauthorized access to network resources.
Organizations should implement immediate mitigation strategies including mandatory firmware updates to the patched versions provided by QNAP, which address the cleartext storage issue through proper encryption of session cookies and implementation of secure session management protocols. The recommended remediation approach includes not only updating to the specified patched versions but also implementing network monitoring to detect potential exploitation attempts and conducting thorough security assessments of all QNAP installations. Additional protective measures should encompass mandatory use of HTTPS protocols for all web-based administration interfaces, implementation of secure network segmentation, and regular security audits to ensure proper encryption of all session data. From an ATT&CK framework perspective, this vulnerability maps to T1566 (Phishing) and T1071.001 (Application Layer Protocol: Web Protocols) as attackers can leverage the cleartext session information to establish persistent access. The mitigation strategy should also include network-based detection mechanisms to identify suspicious cookie handling patterns and ensure that all web applications within the QNAP ecosystem properly implement secure session management practices. Organizations should also consider implementing additional security controls such as multi-factor authentication and privileged access management solutions to reduce the overall risk exposure associated with this vulnerability.