CVE-2021-39181 Explained : Impact and Mitigation

OpenOlat is a web-based learning management system (LMS) affected by unsafe deserialization of user data using XStream. The vulnerability allows an attacker to execute arbitrary code by leveraging a prepared import XML file.

Understanding CVE-2021-39181

This CVE details the vulnerability in OpenOlat that could lead to code execution.

What is CVE-2021-39181?

OpenOlat, prior to versions 15.3.18, 15.5.3, and 16.0.0, allows classes on the Java classpath to be instantiated via a crafted XML file, enabling the execution of arbitrary code.

The Impact of CVE-2021-39181

The CVSS v3.1 base score for this vulnerability is 8.8 (High severity) with a LOW attack complexity and requires privileges on the network.

Technical Details of CVE-2021-39181

This section provides more technical insights into the vulnerability.

Vulnerability Description

The XML injection vulnerability (CWE-91) in OpenOlat could be exploited by an attacker with an OpenOlat user account with the authoring role.

Affected Systems and Versions

Product: OpenOLAT
Vendor: OpenOLAT
Versions affected: < 15.3.18, >= 15.4.0, < 15.5.3

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
Privileges Required: Low
User Interaction: None
Scope: Unchanged

Mitigation and Prevention

Preventive measures to secure systems against CVE-2021-39181.

Immediate Steps to Take

Upgrade OpenOlat to versions 15.3.18, 15.5.3, or 16.0.0 to mitigate the vulnerability.

Long-Term Security Practices

Regularly update and patch OpenOlat to address security flaws.
Monitor and restrict user privileges to minimize the attack surface.

Patching and Updates

Ensure timely installation of security patches and updates to stay protected against known vulnerabilities.