diff --git a/Misc/NEWS b/Misc/NEWS
index 4baf757b5f30..dc375d0e0321 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -50,6 +50,9 @@ Core and Builtins
   __bytes__, __trunc__, and __float__ returning instances of subclasses of
   bytes, int, and float to subclasses of bytes, int, and float correspondingly.
 
+- Issue #26171: Fix possible integer overflow and heap corruption in
+  zipimporter.get_data().
+
 Library
 -------
 
diff --git a/Modules/zipimport.c b/Modules/zipimport.c
index 42f8f161851a..fa60aa9e0a5b 100644
--- a/Modules/zipimport.c
+++ b/Modules/zipimport.c
@@ -1127,6 +1127,11 @@ get_data(PyObject *archive, PyObject *toc_entry)
     }
     file_offset += l;           /* Start of file data */
 
+    if (data_size > LONG_MAX - 1) {
+        fclose(fp);
+        PyErr_NoMemory();
+        return NULL;
+    }
     bytes_size = compress == 0 ? data_size : data_size + 1;
     if (bytes_size == 0)
         bytes_size++;