CVE-2017-12933 : Security Advisory and Response

PHP Vulnerability in finish_nested_data Function

Understanding CVE-2017-12933

What is CVE-2017-12933?

CVE-2017-12933 is a vulnerability found in PHP versions prior to 5.6.31, 7.0.x before 7.0.21, and 7.1.x before 7.1.7. The vulnerability exists in the finish_nested_data function in ext/standard/var_unserializer.re, potentially leading to a buffer over-read when unserializing untrusted data.

The Impact of CVE-2017-12933

If exploited, this vulnerability can compromise the integrity of PHP, allowing attackers to cause potential damage.

Technical Details of CVE-2017-12933

Vulnerability Description

The finish_nested_data function in PHP versions before 5.6.31, 7.0.x before 7.0.21, and 7.1.x before 7.1.7 is susceptible to a buffer over-read during the unserialization of untrusted data.

Affected Systems and Versions

PHP versions prior to 5.6.31
PHP 7.0.x before 7.0.21
PHP 7.1.x before 7.1.7

Exploitation Mechanism

Attackers can exploit this vulnerability by providing malicious serialized data, triggering a buffer over-read and potentially compromising the PHP integrity.

Mitigation and Prevention

Immediate Steps to Take

Update PHP to versions 5.6.31, 7.0.21, or 7.1.7 or later to patch the vulnerability.
Avoid unserializing untrusted data in PHP applications.

Long-Term Security Practices

Regularly monitor PHP security advisories and update PHP promptly.
Implement input validation and data sanitization to prevent malicious data exploitation.

Patching and Updates

Apply security patches provided by PHP to address the vulnerability.