CVE-2018-3770 in markdown-pdf
Summary
by MITRE
A path traversal exists in markdown-pdf version <9.0.0 that allows a user to insert a malicious html code that can result in reading the local files.
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Analysis
by VulDB Data Team • 03/09/2020
The vulnerability identified as CVE-2018-3770 resides within the markdown-pdf library version 8.0.0 and earlier, representing a critical path traversal flaw that enables arbitrary file access through malicious HTML code injection. This vulnerability specifically affects applications that utilize the markdown-pdf package to convert markdown documents into PDF format, creating a dangerous attack surface where user-controlled input can be manipulated to access sensitive local files on the server. The flaw occurs during the HTML processing phase of PDF generation, where the library fails to properly sanitize or validate file paths that are included within the markdown content, particularly when HTML elements are embedded within the document structure.
The technical implementation of this vulnerability stems from inadequate input validation and path sanitization mechanisms within the markdown-pdf processing pipeline. When users provide markdown content containing HTML elements that reference local files or paths, the library does not properly restrict these references, allowing attackers to craft malicious markdown documents that include relative path traversal sequences such as ../ or ../../. This enables attackers to navigate the file system and access files that should remain protected, including configuration files, database credentials, system logs, and other sensitive data stored on the same server hosting the vulnerable application. The vulnerability operates at the application layer and can be exploited through any interface that accepts markdown input and processes it through the affected library version.
The operational impact of CVE-2018-3770 extends beyond simple information disclosure, as it provides attackers with the capability to potentially escalate privileges and gain deeper access to compromised systems. Attackers can leverage this vulnerability to read system configuration files, application source code, user credentials, and other sensitive materials that may be stored in predictable locations on the server. The vulnerability is particularly dangerous in environments where the markdown-pdf library is used in web applications, content management systems, or collaborative platforms where users can submit content that gets processed into PDF documents. According to CWE classification, this vulnerability maps to CWE-22 Path Traversal, which is categorized as a high-severity issue in the Common Weakness Enumeration catalog. The attack pattern aligns with ATT&CK technique T1083 File and Directory Discovery, as it enables adversaries to explore the file system and identify valuable targets for further exploitation.
Mitigation strategies for CVE-2018-3770 primarily focus on immediate version updates to markdown-pdf 9.0.0 or later, which includes proper input sanitization and path validation mechanisms. Organizations should implement comprehensive input validation at multiple layers, including application-level sanitization of user-provided markdown content and the implementation of strict file access controls that prevent traversal beyond designated directories. Additionally, security measures such as sandboxing the PDF generation process, implementing proper file system permissions, and using secure coding practices that enforce least privilege access should be deployed. The vulnerability highlights the importance of dependency management and regular security audits of third-party libraries, particularly those handling user input and file operations. Organizations should also consider implementing web application firewalls and content filtering mechanisms to detect and block suspicious file path references in markdown content, while maintaining detailed logging and monitoring of file access patterns to identify potential exploitation attempts.