In PHP versions 8.1.* before 8.1.34, 8.2.* before 8.2.30, 8.3.* before 8.3.29, 8.4.* before 8.4.16, 8.5.* before 8.5.1 when using the PDO PostgreSQL driver with PDO::ATTR_EMULATE_PREPARES enabled, an invalid character sequence (such as \x99) in a prepared statement parameter may cause the quoting function PQescapeStringConn to return NULL, leading to a null pointer dereference in pdo_parse_params() function. This may lead to crashes (segmentation fault) and affect the availability of the target server.