libvips unpremultiply.c vips_unpremultiply_build out-of-bounds

A flaw has been found in libvips 8.19.0. This vulnerability affects the function vips_unpremultiply_build of the file libvips/conversion/unpremultiply.c. Executing a manipulation of the argument alpha_band can lead to out-of-bounds read. The attack needs to be launched locally. The exploit has been published and may be used. This patch is called 7215ead1e0cd7d3703cc4f5fca06d7d0f4c22b91. A patch should be applied to remediate this issue.