Overview
This report discusses CVE-2025-27409, a significant path traversal vulnerability identified in Joplin Server. The vulnerability, present in versions prior to 3.3.3, exposes users to potential system compromise and data leakage. As a popular open-source note-taking and to-do application, Joplin’s vulnerability could impact a substantial number of users and their sensitive data, underlining the importance of understanding and mitigating this security flaw.
Vulnerability Summary
CVE ID: CVE-2025-27409
Severity: High (7.5)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
Joplin Server | Prior to 3.3.3
How the Exploit Works
The path traversal vulnerability exists in Joplin Server’s handling of file paths that start with `css/pluginAssets` or `js/pluginAssets`. Specifically, the `findLocalFile` function in the default route calls `localFileFromUrl` to check for special `pluginAssets` paths. If a path is returned, the result is directly returned without checking for path traversal. This oversight allows an attacker to manipulate file paths to access files outside the intended directories and hence, potentially compromise the system or leak data.
Conceptual Example Code
A conceptual example of exploiting this vulnerability could involve an HTTP request designed to manipulate the `pluginAssets` path. This would look something like:
GET /css/pluginAssets/../../../../etc/passwd HTTP/1.1
Host: target.example.comIn this example, the `../../../../etc/passwd` is used to traverse up the directory tree to an unintended location, potentially reading sensitive system files.
Mitigation Guidance
Users are strongly advised to apply the vendor patch by updating to Joplin Server version 3.3.3 or newer, which contains a fix for the issue. As a temporary mitigation, users can employ a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and block malicious path traversal attempts.
