this release patches a critical vulnerability that occurs when the DEFLATE backend attempts to compress very short inputs (less than 3 bytes) causing a runtime crash.
for applications using the library for PNG compression, the attack is only effective if the server is asked to compress a 1x1 pixel grayscale image, as all other types of PNG images create data streams that are longer than 2 bytes.
all Swift PNG users are advised to upgrade to 4.4.1 immediately.