CVE-2025-12495 CVE-2025-12839 CVE-2025-12840: fix heap buffer overflows
in the C core decoding pipeline (missing nread validation in
exrreadchunk, missing packed/unpacked size check for uncompressed tiles,
missing storage_mode guard in chunk offset computation)
CVE-2025-64181: fix use of uninitialized memory caused by incompletely
populated scratch buffers (addressed by the same precondition guards in
chunk.c and parse_header.c)