diff -urNp a/IlmImf/ImfRleCompressor.cpp b/IlmImf/ImfRleCompressor.cpp
--- a/IlmImf/ImfRleCompressor.cpp	2020-06-02 12:29:00.823667417 +0200
+++ b/IlmImf/ImfRleCompressor.cpp	2020-06-02 12:32:51.134011377 +0200
@@ -135,6 +135,11 @@ rleUncompress (int inLength, int maxLeng
 	    if (0 > (maxLength -= count))
 		return 0;
 
+        // check the input buffer is big enough to contain
+        // 'count' bytes of remaining data
+        if (inLength < 0)
+          return 0;
+
 	    while (count-- > 0)
 		*out++ = *(char *) (in++);
 	}