CVE-2025-59733

When decoding an OpenEXR file that uses DWAA or DWAB compression, there's an implicit assumption that all image channels have the same pixel type (and size), and that if there are four channels, the first four are "B", "G", "R"and "A". The channel parsing code can be found in decode_header.The buffer td->uncompressed_datais allocated in decode_blockbased on the xsize, ysizeand computed current_channel_offset.

The function dwa_uncompressthen assumes at [5] that if there are 4 channels, these are "B", "G", "R"and "A", and in the calculations at [6] and [7] that all channels are of the same type, which matches the type of the main color channels.

If we set the main color channels to a 4-byte type and add duplicate or unknown channels of the 2-byte EXR_HALFtype, then the addition at [7] will increment the pointer by 4-bytes * xsize * nb_channels, which will exceed the allocated buffer.





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