When opening a Hangul Hcell Document (.cell) and processing a record that uses the CSSValFormat object, Hancom Office 2014 will search for an underscore ("_") character at the end of the string and write a null terminator after it. If the character is at the very end of the string, the application will mistakenly write the null-byte outside the bounds of its destination. This can result in heap corruption that can lead code execution under the context of the application