A social issue is a problem that affects many people within a society. According to Marxism, social issues tend to arise due to contradictions of society's mode of production. Nowadays, given that capitalism is the dominant mode of production in the world, it's safe to say that modern societal problems are a product of capitalism that are globally exported to all countries, exactly because of this dominant character.
Problems such as poverty, food insecurity, violence, homelessness, pollution, etc. arise from the way things are produced and distributed and these problems are preserved through capitalism's enforcement of class society.
While such problems have existed in the past, they have today a character that is unique to capitalism. That is, food insecurity under feudalism was different (had different causes and repercussions) to food insecurity in capitalism.