Description
PHP before 4.4.3 and 5.x before 5.1.4 does not limit the character set of the session identifier (PHPSESSID) for third party session handlers, which might make it easier for remote attackers to exploit other vulnerabilities by inserting PHP code into the PHPSESSID, which is stored in the session file. NOTE: it could be argued that this not a vulnerability in PHP itself, rather a design limitation that enables certain attacks against session handlers that do not account for this limitation.
Remediation
References
Related Vulnerabilities
Oracle Database Server Other Vulnerability (CVE-2007-3855)
LimeSurvey Improper Neutralization of Formula Elements in a CSV File Vulnerability (CVE-2019-16184)
WordPress Plugin Floating Tweets Multiple Vulnerabilities (1.0.1)
PHP Improper Input Validation Vulnerability (CVE-2016-4072)
WordPress Plugin Uncanny Toolkit for LearnDash Cross-Site Request Forgery (3.6.4.1)