The Cascading Style Sheets (CSS) implementation in Opera before 11.11 does not properly handle the column-count property, which allows remote attackers to cause a denial of service (infinite repaint loop and application hang) via a web page, as demonstrated by an unspecified Wikipedia page.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.