SECURITY UPDATE: Heap buffer over-read in pngwriteimage_* due to
truncation of ptrdifft row stride to pnguint16
debian/patches/CVE-2026-22801.patch: remove incorrect truncation
casts from pngwriteimage16bit, pngwriteimage8bit, and
pngimagewrite
main so large (>65535) and negative row strides
are handled correctly
CVE-2026-22801
SECURITY UPDATE: Heap buffer overflow in pngsetquantize due to
stale palette indices stored in the color distance hash table
debian/patches/CVE-2026-25646.patch: store original palette
indices via palettetoindex in pngsetquantize so the
color-pruning loop does not read past the 769-element hash array