CVE-2021-39183 : Security Advisory and Response
CVE-2021-39183, also known as 'Unsafe inline XSS Owncast,' is a high-severity vulnerability in Owncast versions below 0.0.9. Understand the impact, affected systems, exploitation mechanism, and mitigation steps.
Owncast is an open-source, self-hosted live video streaming and chat server that had a vulnerability allowing the execution of inline scripts when Javascript is parsed via a paste action. This issue is patched in version 0.0.9 by blocking unsafe-inline Content Security Policy.
Understanding CVE-2021-39183
This section provides an overview and impact of the vulnerability.
What is CVE-2021-39183?
CVE-2021-39183, also known as 'Unsafe inline XSS Owncast,' is a vulnerability in Owncast versions below 0.0.9 that allows the execution of inline scripts during JavaScript parsing.
The Impact of CVE-2021-39183
The vulnerability has a CVSS v3.1 base score of 8.2, categorizing it as high severity. It impacts the integrity of affected systems and requires user interaction for exploitation while having a low impact on confidentiality and availability.
Technical Details of CVE-2021-39183
This section delves into the technical aspects of the vulnerability.
Vulnerability Description
The issue originates from inline scripts being executed during JavaScript parsing, leading to a Cross-Site Scripting (XSS) vulnerability.
Affected Systems and Versions
- Product: Owncast
- Vendor: Owncast
- Versions Affected: Below 0.0.9
Exploitation Mechanism
The vulnerability is triggered when JavaScript is parsed through a paste action, enabling malicious actors to execute inline scripts.
Mitigation and Prevention
Learn how to address and prevent the CVE-2021-39183 vulnerability.
Immediate Steps to Take
- Update Owncast to version 0.0.9 or later to block unsafe-inline Content Security Policy.
- Ensure script-src is specified and worker-src is set to blob for the video player.
Long-Term Security Practices
- Implement regular security audits to identify and address vulnerabilities promptly.
- Educate developers on secure coding practices to mitigate XSS and other web-based attacks.
Patching and Updates
- Stay informed about security advisories and patches released by Owncast to address known vulnerabilities.