The odbc_bindcols function in ext/odbc/php_odbc.c in PHP before 5.6.12 mishandles driver behavior for SQL_WVARCHAR columns, which allows remote attackers to cause a denial of service (application crash) in opportunistic circumstances by leveraging use of the odbc_fetch_array function to access a certain type of Microsoft SQL Server table.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2015-8735
https://bugs.php.net/bug.php?id=69975