CVE-2026-34380: fix signed 32-bit integer overflow in the PXR24 decoder
bounds check, where (uint64_t) (w * 3) wrapped to a small positive value
and allowed an out-of-bounds write through dout
CVE-2026-34378: fix signed 32-bit integer overflow in srcbuffer pointer
arithmetic in the unpack_* routines, reached via an oversized dataWindow
width