CVE-2020-26286 Explained : Impact and Mitigation

HedgeDoc is a collaborative platform for writing and sharing markdown. In HedgeDoc before version 1.7.1, an unauthenticated attacker can upload arbitrary files to the upload storage backend, including HTML, JS, and PHP files. The issue is patched in HedgeDoc 1.7.1. Users are advised to verify the uploaded file storage contents and apply workarounds to enhance security.

Understanding CVE-2020-26286

HedgeDoc vulnerability allowing unauthenticated file uploads.

What is CVE-2020-26286?

CVE-2020-26286 is a vulnerability in HedgeDoc that permits unauthenticated attackers to upload various file types to the upload storage backend, potentially leading to arbitrary code execution.

The Impact of CVE-2020-26286

The vulnerability has a CVSS base score of 7.5, indicating a high severity issue. It can result in the compromise of the integrity of the affected system without requiring privileges or user interaction.

Technical Details of CVE-2020-26286

Details of the vulnerability in HedgeDoc.

Vulnerability Description

CWE-434: Unrestricted Upload of File with Dangerous Type
Unauthenticated attackers can upload HTML, JS, and PHP files to the upload storage backend.

Affected Systems and Versions

Product: HedgeDoc
Vendor: HedgeDoc
Versions Affected: < 1.7.1

Exploitation Mechanism

Attack Vector: Network
Attack Complexity: Low
Integrity Impact: High
Scope: Unchanged
No privileges required

Mitigation and Prevention

Protecting systems from CVE-2020-26286.

Immediate Steps to Take

Upgrade HedgeDoc to version 1.7.1 or later to apply the patch.
Verify and restrict the file types and names allowed in the upload storage.
Block the

/uploadimage

endpoint on the instance using a reverse proxy.

Long-Term Security Practices

Regularly monitor and audit the file upload functionality for unauthorized activities.
Educate users on safe file upload practices to prevent malicious uploads.

Patching and Updates

Apply all security patches and updates provided by HedgeDoc promptly to mitigate known vulnerabilities.