CVE-2020-13449 in Gotenberg
Summary
by MITRE • 01/08/2021
A directory traversal vulnerability in the Markdown engine of Gotenberg through 6.2.1 allows an attacker to read any container files.
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Analysis
by VulDB Data Team • 07/01/2024
The directory traversal vulnerability identified in Gotenberg versions 6.2.1 and earlier represents a critical security flaw that enables attackers to access arbitrary files within the containerized environment. This vulnerability specifically affects the Markdown engine component of the application, which processes user-supplied markdown content and converts it to various formats including PDF, PNG, and HTML. The flaw stems from insufficient input validation and sanitization of file paths during the rendering process, allowing malicious actors to manipulate path parameters and bypass normal file access controls.
This vulnerability operates at the core of how Gotenberg handles file operations within its containerized framework, where the Markdown engine processes user inputs without proper path validation mechanisms. The attack vector typically involves crafting specially formatted markdown content that includes directory traversal sequences such as ../ or ..\ which are then processed by the underlying rendering engine. When these sequences are not properly sanitized, they can cause the system to resolve paths outside of intended directories, potentially exposing sensitive files including configuration data, credentials, application source code, and other container resources.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to sensitive system resources within the container environment. Depending on the container configuration and file permissions, successful exploitation could lead to unauthorized access to database connection strings, API keys, application secrets, or even system-level files that could facilitate further compromise. The vulnerability is particularly concerning in containerized deployments where proper isolation may be compromised, allowing attackers to potentially escalate privileges or gain access to other services running on the same host.
From a cybersecurity perspective, this vulnerability aligns with CWE-22 (Improper Limiting of a Pathname to a Restricted Directory) and represents a classic path traversal attack pattern that has been documented across numerous applications and frameworks. The ATT&CK framework categorizes this as a privilege escalation technique under T1059 (Command and Scripting Interpreter) and potentially T1566 (Phishing) when combined with social engineering approaches to deliver malicious markdown content. Organizations utilizing Gotenberg in production environments should immediately implement mitigation strategies including input validation, path normalization, and container hardening measures. The most effective immediate solution involves updating to version 6.2.2 or later where the vulnerability has been patched, along with implementing proper access controls, file system restrictions, and monitoring for suspicious file access patterns.
Security teams should also consider implementing network segmentation and container runtime security controls to limit potential damage from successful exploitation attempts. Regular vulnerability assessments and penetration testing should include verification of path traversal protections in all file processing components, particularly those handling user-supplied content. The incident highlights the importance of validating all external inputs and implementing defense-in-depth strategies that protect against common attack patterns including directory traversal, injection attacks, and privilege escalation techniques that could be leveraged to compromise containerized applications.