diff --git a/Modules/zipimport.c b/Modules/zipimport.c
--- a/Modules/zipimport.c
+++ b/Modules/zipimport.c
@@ -861,6 +861,10 @@ get_data(char *archive, PyObject *toc_en
                           &date, &crc)) {
         return NULL;
     }
+    if (data_size < 0) {
+        PyErr_Format(ZipImportError, "negative data size");
+        return NULL;
+    }
 
     fp = fopen(archive, "rb");
     if (!fp) {
@@ -895,6 +895,11 @@ get_data(char *archive, PyObject *toc_en
         PyMarshal_ReadShortFromFile(fp);        /* local header size */
     file_offset += l;           /* Start of file data */
 
+    if (data_size > LONG_MAX - 1) {
+        fclose(fp);
+        PyErr_NoMemory();
+        return NULL;
+    }
     raw_data = PyString_FromStringAndSize((char *)NULL, compress == 0 ?
                                           data_size : data_size + 1);
     if (raw_data == NULL) {