CVE-2018-20745 : What You Need to Know

Yii 2.x up to 2.0.15.1 changes a wildcard CORS policy to reflect an unpredictable Origin header value, potentially leading to security issues.

Understanding CVE-2018-20745

Versions of Yii 2.x up to 2.0.15.1 have a vulnerability related to CORS policy manipulation.

What is CVE-2018-20745?

Yii 2.x versions up to 2.0.15.1 convert a wildcard CORS policy to mirror an arbitrary Origin header value, deviating from CORS security principles.

The Impact of CVE-2018-20745

This behavior can result in security issues due to misconfigurations in CORS, potentially exposing systems to attacks.

Technical Details of CVE-2018-20745

This section provides more technical insights into the vulnerability.

Vulnerability Description

Yii 2.x through 2.0.15.1 actively converts a wildcard CORS policy into reflecting an arbitrary Origin header value, which is incompatible with the CORS security design.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions affected: Up to 2.0.15.1

Exploitation Mechanism

The vulnerability arises from the incorrect handling of CORS policies, allowing an attacker to potentially exploit misconfigured CORS settings.

Mitigation and Prevention

Protecting systems from CVE-2018-20745 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Yii framework to a patched version that addresses the CORS vulnerability.
Review and adjust CORS policies to ensure they follow security best practices.

Long-Term Security Practices

Regularly monitor and audit CORS configurations for any anomalies.
Educate developers on secure CORS policy implementation to prevent similar issues.

Patching and Updates

Apply patches or updates provided by Yii to fix the CORS vulnerability and enhance system security.