CVE-2021-29474 : Exploit Details and Defense Strategies

HedgeDoc (formerly known as CodiMD) is an open-source collaborative markdown editor that is vulnerable to a Relative Path Traversal Attack on note creation, allowing an attacker to read arbitrary

.md

files from the server's filesystem. This article explores the impact, technical details, and mitigation strategies related to CVE-2021-29474.

Understanding CVE-2021-29474

This section delves into what CVE-2021-29474 entails.

What is CVE-2021-29474?

CVE-2021-29474 is a vulnerability in HedgeDoc that enables an attacker to read arbitrary

.md

files from the server's filesystem through a Relative Path Traversal Attack.

The Impact of CVE-2021-29474

The impact of CVE-2021-29474 is moderate, with a CVSS v3.1 base score of 4.7, and primarily affects confidentiality with low integrity impact and no availability impact. The attack complexity is low, requiring network access and user interaction.

Technical Details of CVE-2021-29474

This section provides technical details of the vulnerability.

Vulnerability Description

The vulnerability arises from improper input validation in HedgeDoc, allowing an attacker to perform a relative path traversal and access

.md

files on the server's filesystem.

Affected Systems and Versions

HedgeDoc versions prior to 1.8.0 are affected by this vulnerability.

Exploitation Mechanism

The exploitation involves passing a URL-encoded alias to the

noteController.showNote

function, which leads to reading arbitrary

.md

files from the filesystem.

Mitigation and Prevention

This section outlines steps to mitigate and prevent exploitation of CVE-2021-29474.

Immediate Steps to Take

To mitigate the vulnerability, upgrade HedgeDoc to version 1.8.0 or later and ensure proper input validation to prevent path traversal attacks.

Long-Term Security Practices

Implement strict input validation checks, use proper file permissions, and consider additional security measures like chroot or containers to enhance system security.

Patching and Updates

Regularly update HedgeDoc to the latest version and stay informed about security advisories to protect against known vulnerabilities.