Ilfak Guilfanov (Russian: Ильфак Гильфанов, born 1966) is a software developer, computer security researcher and blogger. He became well known when he issued a free hotfix for the Windows Metafile vulnerability on 31 December 2005. His unofficial patch was favorably reviewed and widely publicized because no official patch was initially available from Microsoft. Microsoft released an official patch on 5 January 2006.