CVE-2026-49995 in Tautulli
Summary
by MITRE • 09/21/2026
Tautulli is a Python based monitoring and tracking tool for Plex Media Server. Prior to 2.17.2, the newsletter cron field stored in the newsletters table is inserted by data/interfaces/default/newsletter_config.html into a JavaScript string without safe JSON encoding. An administrator or caller with the Tautulli API key can store a crafted cron value, and an administrator who later opens the newsletter configuration modal passively triggers script execution in the Tautulli web context. The stored value persists in the database and can continue to execute after credential rotation until it is removed. This issue is fixed in version 2.17.2.
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Analysis
by VulDB Data Team • 09/21/2026
Tautulli serves as a comprehensive monitoring and tracking application for Plex Media Server, providing users with detailed insights into media consumption patterns and server health. The software operates within a web-based interface that relies on dynamic content generation to present configuration options and status updates to administrators. In versions prior to 2.17.2, the architecture of the newsletter configuration module contained a critical input validation flaw related to how user-supplied data was handled during serialization for client-side execution. Specifically, when an administrator or any entity possessing a valid Tautulli API key submitted a cron expression via the newsletter configuration interface, this value was inserted directly into a JavaScript string without proper JSON encoding or sanitization. This lack of safe encoding creates a vector for Stored Cross-Site Scripting, as the malicious payload is not merely processed in isolation but is persisted within the application's database and subsequently rendered by the browser when the corresponding administrative modal is accessed.
The technical nature of this vulnerability aligns with CWE-79, which classifies improper neutralization of input during web page generation known commonly as Cross-Site Scripting. The flaw stems from a failure to apply context-appropriate encoding before embedding user-controlled data into JavaScript code blocks. Because the newsletter cron field is stored in the newsletters table and later retrieved for display within a modal dialog box, any crafted value containing executable script tags or event handlers becomes part of the client-side execution environment. This design allows an attacker with API access to plant persistent malicious payloads that do not require immediate exploitation upon submission but rather activate passively when another administrator views the newsletter settings. The persistence mechanism ensures that the vulnerability remains active even if credentials are rotated, as the injected code resides in the database and continues to execute for any subsequent user accessing the affected interface until manual remediation occurs.
From an operational perspective, this Stored Cross-Site Scripting vulnerability poses significant risks to the integrity of the Tautulli administration console. An attacker can leverage this flaw to steal session cookies or authentication tokens associated with active administrator sessions by injecting scripts that exfiltrate data to a remote server controlled by the adversary. Furthermore, the malicious script could manipulate the DOM to perform actions on behalf of the authenticated user, such as altering system configurations, disabling security features, or redirecting traffic. Since Tautulli often holds sensitive information regarding media libraries and user activity, compromising an administrator session can lead to broader privacy violations or serve as a foothold for further attacks against the Plex Media Server infrastructure if lateral movement is possible within the network environment.
The mitigation strategy involves upgrading Tautulli to version 2.17.2 or later, where the developers have implemented proper JSON encoding and input sanitization procedures when handling newsletter configuration data. For environments that cannot immediately upgrade, administrators should audit existing entries in the newsletters table for any anomalous cron expressions containing script tags or encoded JavaScript payloads and remove them manually. Additionally, implementing strict Content Security Policy headers can help mitigate the impact of such vulnerabilities by restricting the sources from which scripts are allowed to execute. This incident highlights the importance of treating all user-supplied data as untrusted, regardless of whether it is displayed in a form field or stored for later retrieval, and underscores the need for rigorous input validation across all API endpoints that interact with persistent storage mechanisms.