diff --git a/Classes/PHPExcel/Worksheet/CellIterator.php b/Classes/PHPExcel/Worksheet/CellIterator.php
index 4b968167..77c5d2e3 100644
--- a/Classes/PHPExcel/Worksheet/CellIterator.php
+++ b/Classes/PHPExcel/Worksheet/CellIterator.php
@@ -35,47 +35,28 @@
  * @package    PHPExcel_Worksheet
  * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
  */
-class PHPExcel_Worksheet_CellIterator implements Iterator
+abstract class PHPExcel_Worksheet_CellIterator
 {
 	/**
 	 * PHPExcel_Worksheet to iterate
 	 *
 	 * @var PHPExcel_Worksheet
 	 */
-	private $_subject;
-
-	/**
-	 * Row index
-	 *
-	 * @var int
-	 */
-	private $_rowIndex;
+	protected $_subject;
 
 	/**
 	 * Current iterator position
 	 *
-	 * @var int
+	 * @var mixed
 	 */
-	private $_position = 0;
+	protected $_position = null;
 
 	/**
-	 * Loop only existing cells
+	 * Iterate only existing cells
 	 *
 	 * @var boolean
 	 */
-	private $_onlyExistingCells = true;
-
-	/**
-	 * Create a new cell iterator
-	 *
-	 * @param PHPExcel_Worksheet 		$subject
-	 * @param int						$rowIndex
-	 */
-	public function __construct(PHPExcel_Worksheet $subject = null, $rowIndex = 1) {
-		// Set subject and row index
-		$this->_subject 	= $subject;
-		$this->_rowIndex 	= $rowIndex;
-	}
+	protected $_onlyExistingCells = false;
 
 	/**
 	 * Destructor
@@ -84,63 +65,6 @@ class PHPExcel_Worksheet_CellIterator implements Iterator
 		unset($this->_subject);
 	}
 
-	/**
-	 * Rewind iterator
-	 */
-    public function rewind() {
-        $this->_position = 0;
-    }
-
-    /**
-     * Current PHPExcel_Cell
-     *
-     * @return PHPExcel_Cell
-     */
-    public function current() {
-		return $this->_subject->getCellByColumnAndRow($this->_position, $this->_rowIndex);
-    }
-
-    /**
-     * Current key
-     *
-     * @return int
-     */
-    public function key() {
-        return $this->_position;
-    }
-
-    /**
-     * Next value
-     */
-    public function next() {
-        ++$this->_position;
-    }
-
-    /**
-     * Are there any more PHPExcel_Cell instances available?
-     *
-     * @return boolean
-     */
-    public function valid() {
-        // columnIndexFromString() returns an index based at one,
-        // treat it as a count when comparing it to the base zero
-        // position.
-        $columnCount = PHPExcel_Cell::columnIndexFromString($this->_subject->getHighestColumn());
-
-        if ($this->_onlyExistingCells) {
-            // If we aren't looking at an existing cell, either
-            // because the first column doesn't exist or next() has
-            // been called onto a nonexistent cell, then loop until we
-            // find one, or pass the last column.
-            while ($this->_position < $columnCount &&
-                   !$this->_subject->cellExistsByColumnAndRow($this->_position, $this->_rowIndex)) {
-                ++$this->_position;
-            }
-        }
-
-        return $this->_position < $columnCount;
-    }
-
 	/**
 	 * Get loop only existing cells
 	 *
@@ -150,12 +74,23 @@ class PHPExcel_Worksheet_CellIterator implements Iterator
     	return $this->_onlyExistingCells;
     }
 
+	/**
+	 * Validate start/end values for "IterateOnlyExistingCells" mode, and adjust if necessary
+	 *
+     * @throws PHPExcel_Exception
+	 */
+    abstract protected function adjustForExistingOnlyRange() {
+    }
+
 	/**
 	 * Set the iterator to loop only existing cells
 	 *
 	 * @param	boolean		$value
+     * @throws PHPExcel_Exception
 	 */
     public function setIterateOnlyExistingCells($value = true) {
-    	$this->_onlyExistingCells = $value;
+    	$this->_onlyExistingCells = (boolean) $value;
+
+        $this->adjustForExistingOnlyRange();
     }
 }
diff --git a/Classes/PHPExcel/Worksheet/ColumnCellIterator.php b/Classes/PHPExcel/Worksheet/ColumnCellIterator.php
index ac4c87a2..a9ef49f0 100644
--- a/Classes/PHPExcel/Worksheet/ColumnCellIterator.php
+++ b/Classes/PHPExcel/Worksheet/ColumnCellIterator.php
@@ -35,49 +35,28 @@
  * @package	PHPExcel_Worksheet
  * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
  */
-class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
+class PHPExcel_Worksheet_ColumnCellIterator extends PHPExcel_Worksheet_CellIterator implements Iterator
 {
-	/**
-	 * PHPExcel_Worksheet to iterate
-	 *
-	 * @var PHPExcel_Worksheet
-	 */
-	private $_subject;
-
 	/**
 	 * Column index
 	 *
 	 * @var string
 	 */
-	private $_columnIndex;
+	protected $_columnIndex;
 
-	/**
-	 * Current iterator position
-	 *
-	 * @var int
-	 */
-	private $_position = 1;
-
-	/**
+    /**
 	 * Start position
 	 *
 	 * @var int
 	 */
-	private $_startRow = 1;
+	protected $_startRow = 1;
 
 	/**
 	 * End position
 	 *
 	 * @var int
 	 */
-	private $_endRow = 1;
-
-	/**
-	 * Loop only existing cells
-	 *
-	 * @var boolean
-	 */
-	private $_onlyExistingCells = true;
+	protected $_endRow = 1;
 
 	/**
 	 * Create a new row iterator
@@ -106,10 +85,12 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
 	 * (Re)Set the start row and the current row pointer
 	 *
 	 * @param integer	$startRow	The row number at which to start iterating
-     * @return PHPExcel_Worksheet_RowIterator
+     * @return PHPExcel_Worksheet_ColumnCellIterator
+     * @throws PHPExcel_Exception
 	 */
 	public function resetStart($startRow = 1) {
 		$this->_startRow = $startRow;
+        $this->adjustForExistingOnlyRange();
 		$this->seek($startRow);
 
         return $this;
@@ -119,10 +100,12 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
 	 * (Re)Set the end row
 	 *
 	 * @param integer	$endRow	The row number at which to stop iterating
-     * @return PHPExcel_Worksheet_RowIterator
+     * @return PHPExcel_Worksheet_ColumnCellIterator
+     * @throws PHPExcel_Exception
 	 */
 	public function resetEnd($endRow = null) {
 		$this->_endRow = ($endRow) ? $endRow : $this->_subject->getHighestRow();
+        $this->adjustForExistingOnlyRange();
 
         return $this;
 	}
@@ -131,12 +114,14 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
 	 * Set the row pointer to the selected row
 	 *
 	 * @param integer	$row	The row number to set the current pointer at
-     * @return PHPExcel_Worksheet_RowIterator
+     * @return PHPExcel_Worksheet_ColumnCellIterator
      * @throws PHPExcel_Exception
 	 */
 	public function seek($row = 1) {
         if (($row < $this->_startRow) || ($row > $this->_endRow)) {
             throw new PHPExcel_Exception("Row $row is out of range ({$this->_startRow} - {$this->_endRow})");
+        } elseif ($this->_onlyExistingCells && !($this->_subject->cellExistsByColumnAndRow($this->_columnIndex, $row))) {
+            throw new PHPExcel_Exception('In "IterateOnlyExistingCells" mode and Cell does not exist');
         }
 		$this->_position = $row;
 
@@ -151,7 +136,7 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
 	}
 
 	/**
-	 * Return the current row in this worksheet
+	 * Return the current cell in this worksheet column
 	 *
 	 * @return PHPExcel_Worksheet_Row
 	 */
@@ -172,7 +157,11 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
 	 * Set the iterator to its next value
 	 */
 	public function next() {
-		++$this->_position;
+        do {
+            ++$this->_position;
+        } while (($this->_onlyExistingCells) &&
+            (!$this->_subject->cellExistsByColumnAndRow($this->_columnIndex, $this->_position)) &&
+            ($this->_position <= $this->_endRow));
 	}
 
 	/**
@@ -183,7 +172,11 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
             throw new PHPExcel_Exception("Row is already at the beginning of range ({$this->_startRow} - {$this->_endRow})");
         }
 
-        --$this->_position;
+        do {
+            --$this->_position;
+        } while (($this->_onlyExistingCells) &&
+            (!$this->_subject->cellExistsByColumnAndRow($this->_columnIndex, $this->_position)) &&
+            ($this->_position >= $this->_startRow));
 	}
 
 	/**
@@ -196,20 +189,27 @@ class PHPExcel_Worksheet_ColumnCellIterator implements Iterator
 	}
 
 	/**
-	 * Get loop only existing cells
+	 * Validate start/end values for "IterateOnlyExistingCells" mode, and adjust if necessary
 	 *
-	 * @return boolean
+     * @throws PHPExcel_Exception
 	 */
-    public function getIterateOnlyExistingCells() {
-    	return $this->_onlyExistingCells;
+    protected function adjustForExistingOnlyRange() {
+        if ($this->_onlyExistingCells) {
+            while ((!$this->_subject->cellExistsByColumnAndRow($this->_columnIndex, $this->_startRow)) &&
+                ($this->_startRow <= $this->_endRow)) {
+                ++$this->_startRow;
+            }
+            if ($this->_startRow > $this->_endRow) {
+                throw new PHPExcel_Exception('No cells exist within the specified range');
+            }
+            while ((!$this->_subject->cellExistsByColumnAndRow($this->_columnIndex, $this->_endRow)) &&
+                ($this->_endRow >= $this->_startRow)) {
+                --$this->_endRow;
+            }
+            if ($this->_endRow < $this->_startRow) {
+                throw new PHPExcel_Exception('No cells exist within the specified range');
+            }
+        }
     }
 
-	/**
-	 * Set the iterator to loop only existing cells
-	 *
-	 * @param	boolean		$value
-	 */
-    public function setIterateOnlyExistingCells($value = true) {
-    	$this->_onlyExistingCells = $value;
-    }
 }
diff --git a/Classes/PHPExcel/Worksheet/RowCellIterator.php b/Classes/PHPExcel/Worksheet/RowCellIterator.php
index 048ca9d3..96c6b419 100644
--- a/Classes/PHPExcel/Worksheet/RowCellIterator.php
+++ b/Classes/PHPExcel/Worksheet/RowCellIterator.php
@@ -35,49 +35,28 @@
  * @package	PHPExcel_Worksheet
  * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
  */
-class PHPExcel_Worksheet_RowCellIterator implements Iterator
+class PHPExcel_Worksheet_RowCellIterator extends PHPExcel_Worksheet_CellIterator implements Iterator
 {
-	/**
-	 * PHPExcel_Worksheet to iterate in
-	 *
-	 * @var PHPExcel_Worksheet
-	 */
-	private $_subject;
-
 	/**
 	 * Row index
 	 *
 	 * @var int
 	 */
-	private $_rowIndex;
-
-	/**
-	 * Current iterator position
-	 *
-	 * @var int
-	 */
-	private $_position = 0;
+	protected $_rowIndex;
 
 	/**
 	 * Start position
 	 *
 	 * @var int
 	 */
-	private $_startColumn = 0;
+	protected $_startColumn = 0;
 
 	/**
 	 * End position
 	 *
 	 * @var int
 	 */
-	private $_endColumn = 0;
-
-	/**
-	 * Loop only existing cells
-	 *
-	 * @var boolean
-	 */
-	private $_onlyExistingCells = true;
+	protected $_endColumn = 0;
 
 	/**
 	 * Create a new column iterator
@@ -107,11 +86,13 @@ class PHPExcel_Worksheet_RowCellIterator implements Iterator
 	 *
 	 * @param integer	$startColumn	The column address at which to start iterating
      * @return PHPExcel_Worksheet_RowCellIterator
+     * @throws PHPExcel_Exception
 	 */
 	public function resetStart($startColumn = 'A') {
         $startColumnIndex = PHPExcel_Cell::columnIndexFromString($startColumn) - 1;
 		$this->_startColumn = $startColumnIndex;
-		$this->seek($startColumn);
+        $this->adjustForExistingOnlyRange();
+		$this->seek(PHPExcel_Cell::stringFromColumnIndex($this->_startColumn));
 
         return $this;
 	}
@@ -121,10 +102,12 @@ class PHPExcel_Worksheet_RowCellIterator implements Iterator
 	 *
 	 * @param string	$endColumn	The column address at which to stop iterating
      * @return PHPExcel_Worksheet_RowCellIterator
+     * @throws PHPExcel_Exception
 	 */
 	public function resetEnd($endColumn = null) {
 		$endColumn = ($endColumn) ? $endColumn : $this->_subject->getHighestColumn();
 		$this->_endColumn = PHPExcel_Cell::columnIndexFromString($endColumn) - 1;
+        $this->adjustForExistingOnlyRange();
 
         return $this;
 	}
@@ -140,6 +123,8 @@ class PHPExcel_Worksheet_RowCellIterator implements Iterator
         $column = PHPExcel_Cell::columnIndexFromString($column) - 1;
         if (($column < $this->_startColumn) || ($column > $this->_endColumn)) {
             throw new PHPExcel_Exception("Column $column is out of range ({$this->_startColumn} - {$this->_endColumn})");
+        } elseif ($this->_onlyExistingCells && !($this->_subject->cellExistsByColumnAndRow($column, $this->_rowIndex))) {
+            throw new PHPExcel_Exception('In "IterateOnlyExistingCells" mode and Cell does not exist');
         }
 		$this->_position = $column;
 
@@ -175,7 +160,11 @@ class PHPExcel_Worksheet_RowCellIterator implements Iterator
 	 * Set the iterator to its next value
 	 */
 	public function next() {
-		++$this->_position;
+        do {
+            ++$this->_position;
+        } while (($this->_onlyExistingCells) &&
+            (!$this->_subject->cellExistsByColumnAndRow($this->_position, $this->_rowIndex)) &&
+            ($this->_position <= $this->_endColumn));
 	}
 
 	/**
@@ -192,7 +181,11 @@ class PHPExcel_Worksheet_RowCellIterator implements Iterator
             );
         }
 
-        --$this->_position;
+        do {
+            --$this->_position;
+        } while (($this->_onlyExistingCells) &&
+            (!$this->_subject->cellExistsByColumnAndRow($this->_position, $this->_rowIndex)) &&
+            ($this->_position >= $this->_startColumn));
 	}
 
 	/**
@@ -205,20 +198,27 @@ class PHPExcel_Worksheet_RowCellIterator implements Iterator
 	}
 
 	/**
-	 * Get loop only existing cells
+	 * Validate start/end values for "IterateOnlyExistingCells" mode, and adjust if necessary
 	 *
-	 * @return boolean
+     * @throws PHPExcel_Exception
 	 */
-    public function getIterateOnlyExistingCells() {
-    	return $this->_onlyExistingCells;
+    protected function adjustForExistingOnlyRange() {
+        if ($this->_onlyExistingCells) {
+            while ((!$this->_subject->cellExistsByColumnAndRow($this->_startColumn, $this->_rowIndex)) &&
+                ($this->_startColumn <= $this->_endColumn)) {
+                ++$this->_startColumn;
+            }
+            if ($this->_startColumn > $this->_endColumn) {
+                throw new PHPExcel_Exception('No cells exist within the specified range');
+            }
+            while ((!$this->_subject->cellExistsByColumnAndRow($this->_endColumn, $this->_rowIndex)) &&
+                ($this->_endColumn >= $this->_startColumn)) {
+                --$this->_endColumn;
+            }
+            if ($this->_endColumn < $this->_startColumn) {
+                throw new PHPExcel_Exception('No cells exist within the specified range');
+            }
+        }
     }
 
-	/**
-	 * Set the iterator to loop only existing cells
-	 *
-	 * @param	boolean		$value
-	 */
-    public function setIterateOnlyExistingCells($value = true) {
-    	$this->_onlyExistingCells = $value;
-    }
 }
diff --git a/changelog.txt b/changelog.txt
index 0d9b937f..3220049a 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -58,9 +58,10 @@ Planned for v1.8.1
                                                     Improved handling for next/prev
 - Security: (MBaker)                            - XML filescan in XML-based Readers to prevent XML Entity Expansion (XEE)
                                                     (see http://projects.webappsec.org/w/page/13247002/XML%20Entity%20Expansion for an explanation of XEE injection) attacks
+                                                  Reference CVE-2015-3542 - Identification of problem courtesy of Dawid Golunski (Pentest Ltd.)
 
 
-2014-03-02 (v1.8.0):
+                                                  2014-03-02 (v1.8.0):
 - Bugfix:   (MBaker)          Work item CP19830 - Undefined variable: fileHandle in CSV Reader
 - Bugfix:   (MBaker)          Work item CP19968 - Out of memory in style/supervisor.php
 - Bugfix:   (MBaker)                            - Style error with merged cells in PDF Writer