Issue 17538: Document XML vulnerabilties
diff --git a/Doc/library/xml.sax.rst b/Doc/library/xml.sax.rst
index 43d17c2..75cfc11 100644
--- a/Doc/library/xml.sax.rst
+++ b/Doc/library/xml.sax.rst
@@ -16,6 +16,14 @@
SAX exceptions and the convenience functions which will be most used by users of
the SAX API.
+
+.. warning::
+
+ The :mod:`xml.sax` module is not secure against maliciously
+ constructed data. If you need to parse untrusted or unauthenticated data see
+ :ref:`xml-vulnerabilities`.
+
+
The convenience functions are: