CVE-2020-7066 Explained : Impact and Mitigation

PHP versions 7.2.x below 7.2.29, 7.3.x below 7.3.16, and 7.4.x below 7.4.4 are affected by a vulnerability in the get_headers() function that can lead to URL truncation after a null byte, potentially causing data to be sent to the wrong server.

Understanding CVE-2020-7066

This CVE involves a security issue in PHP versions that can impact the proper functioning of the get_headers() function.

What is CVE-2020-7066?

In PHP versions 7.2.x below 7.2.29, 7.3.x below 7.3.16, and 7.4.x below 7.4.4, a vulnerability exists in the get_headers() function. When a user-supplied URL contains a null (\0) character, the URL is truncated at that point. This can lead to incorrect assumptions about the target of get_headers() and potential data leakage to an unintended server.

The Impact of CVE-2020-7066

The vulnerability can result in data being sent to the wrong server due to URL truncation after a null byte, potentially compromising the confidentiality of information.

Technical Details of CVE-2020-7066

This section provides more in-depth technical details about the vulnerability.

Vulnerability Description

The issue arises when using get_headers() with a URL containing a null character, causing the URL to be truncated at that position, leading to potential data leakage.

Affected Systems and Versions

PHP 7.2.x versions below 7.2.29
PHP 7.3.x versions below 7.3.16
PHP 7.4.x versions below 7.4.4

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
Base Score: 5.3 (Medium)
Confidentiality Impact: Low
Integrity Impact: None
Privileges Required: None
User Interaction: None
Scope: Unchanged
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Mitigation and Prevention

Protect your systems from CVE-2020-7066 by following these mitigation strategies.

Immediate Steps to Take

Update PHP to versions 7.2.29, 7.3.16, or 7.4.4 to patch the vulnerability.
Avoid using get_headers() with user-supplied URLs.

Long-Term Security Practices

Regularly update PHP and other software to the latest versions.
Implement input validation to prevent malicious input.

Patching and Updates

Apply the necessary patches provided by PHP Group to address the vulnerability.