Code: static void php_mb_regex_free_cache(php_mb_regex_t **pre) 
 {
 	onig_free(*pre);
 }

Vulnerability Type: DoS Exec Code 
CWE ID: CWE-415
Summary: Double free vulnerability in the _php_mb_regex_ereg_replace_exec function in php_mbregex.c in the mbstring extension in PHP before 5.5.37, 5.6.x before 5.6.23, and 7.x before 7.0.8 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) by leveraging a callback exception.
Commit Message: Fix bug #72402: _php_mb_regex_ereg_replace_exec - double free