File openexr-CVE-2021-20299.patch of Package openexr.22326

diff --git a/OpenEXR/IlmImf/ImfMultiPartInputFile.cpp b/OpenEXR/IlmImf/ImfMultiPartInputFile.cpp
index 689956c90..cbb2ec234 100644
--- a/IlmImf/ImfMultiPartInputFile.cpp
+++ b/IlmImf/ImfMultiPartInputFile.cpp
@@ -340,6 +340,11 @@ MultiPartInputFile::initialize()
     // Perform usual check on headers.
     //
 
+    if ( _data->_headers.size() == 0)
+    {
+        throw IEX_NAMESPACE::ArgExc ("Files must contain at least one header");
+    }
+
     for (size_t i = 0; i < _data->_headers.size(); i++)
     {
         //