GHSA-WQW6-WPR3-45RH fpdf2: Exponential SVG '<use>' expansion causes CPU and memory exhaustion in 'FPDF.image()'

Summary fpdf2 expands SVG references by deep-copying the complete referenced graphics tree. A small SVG can use nested references to make the number of in-memory objects grow exponentially, causing excessive CPU and memory consumption during FPDF.image processing. This was reproduced with an...