It wasn't caught until two days ago, and only because the xz backdoor happened to get caught.
So yeah, more evidence that this happens more frequently than people realize.
Source: https://boehs.org/node/everything-i-know-about-the-xz-backdoor
quotingWhat's really gonna bake your noodle later on is, how many times has this happened before and nobody caught it?
nevent1q…dqcv