GHSA-Q6VJ-WXVF-5M8C OpenEXR has heap-buffer-overflow via signed integer underflow in ImfContextInit.cpp

Summary A heap-buffer-overflow OOB read occurs in the istreamnonparallelread function in ImfContextInit.cpp when parsing a malformed EXR file through a memory-mapped IStream. A signed integer subtraction produces a negative value that is implicitly converted to sizet, resulting in a massive lengt...