CVE-2021-41101 Explained : Impact and Mitigation

CVE-2021-41101 involves too lenient CORS

Access-Control-Allow-Origin

settings in wire-server, affecting versions before 2.106.0.

Understanding CVE-2021-41101

What is CVE-2021-41101?

The vulnerability in wire-server allows for potential Cross-Site Scripting (XSS) attacks due to a lax CORS configuration, posing a risk to user cookies and API access.

The Impact of CVE-2021-41101

The vulnerability has a CVSS base score of 5.7 (Medium severity) with a high impact on confidentiality, requiring user interaction, but with low privileges required.

Technical Details of CVE-2021-41101

Vulnerability Description

Before version 2.106.0, wire-server's CORS configuration allowed any subdomain of

.wire.com

to exploit an XSS vector and access user cookies, potentially leading to API communication.

Affected Systems and Versions

Product: wire-server
Vendor: wireapp
Vulnerable Versions: < 2.106.0

Exploitation Mechanism

The vulnerability arises from the overly permissive CORS

Access-Control-Allow-Origin

header, enabling attackers to misuse XSS vectors on subdomains to access user cookies.

Mitigation and Prevention

Immediate Steps to Take

Limit

Access-Control-Allow-Origin

to requisite apps (account-pages, team-settings, webapp)

Long-Term Security Practices

Implement strict CORS policies tailored to specific application needs

Patching and Updates

A patch is not available; consider limiting CORS permissions and monitoring for any unauthorized access attempts.