CVE-2020-5216 Explained : Impact and Mitigation

Secure Headers (RubyGem secure_headers) before versions 3.9.0, 5.2.0, and 6.3.0 is affected by a directive injection vulnerability that allows limited header injection. This CVE has a CVSS base score of 4.4 (Medium Severity).

Understanding CVE-2020-5216

In this CVE, a newline injection can occur when user-supplied input is passed into append/override_content_security_policy_directives, leading to header injection. Rails silently creates new Content-Security-Policy headers for each newline, affecting versions before 3.9.0, 5.2.0, and 6.3.0.

What is CVE-2020-5216?

CVE-2020-5216 is a vulnerability in Secure Headers (RubyGem secure_headers) that allows for limited header injection when dynamic overrides with user input are used.

The Impact of CVE-2020-5216

The vulnerability has a CVSS base score of 4.4 (Medium Severity) with high attack complexity and requires user interaction. It affects confidentiality and integrity but not availability.

Technical Details of CVE-2020-5216

Secure Headers (RubyGem secure_headers) is affected by a directive injection vulnerability that can lead to limited header injection.

Vulnerability Description

A newline injection vulnerability exists when user input is passed into append/override_content_security_policy_directives, allowing for limited header injection.

Affected Systems and Versions

Versions before 3.9.0
Versions between 5.0.0 and 5.2.0
Versions between 6.0.0 and 6.3.0

Exploitation Mechanism

User-supplied input passed into specific functions can lead to newline injection.
Rails silently creates new headers for each newline encountered.

Mitigation and Prevention

To address CVE-2020-5216, follow these steps:

Immediate Steps to Take

Update Secure Headers to version 3.9.0, 5.2.0, or 6.3.0 to mitigate the vulnerability.
Avoid passing user input directly into functions that manipulate headers.

Long-Term Security Practices

Regularly update dependencies to patched versions.
Implement input validation to prevent malicious input.

Patching and Updates

Apply patches provided by the vendor promptly.