[ci skip] Add a changelog entry for #4963
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index fff1711..b60a909 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -11,6 +11,7 @@
- Fixed an XSS vulnerability in :doc:`Security Library <libraries/security>` method ``xss_clean()``.
- Fixed a possible file inclusion vulnerability in :doc:`Loader Library <libraries/loader>` method ``vars()``.
+ - Fixed a possible remote code execution vulnerability in the :doc:`Email Library <libraries/email>` when 'mail' or 'sendmail' are used (thanks to Paul Buonopane from `NamePros <https://www.namepros.com/>`_).
- Added protection against timing side-channel attacks in :doc:`Security Library <libraries/security>` method ``csrf_verify()``.
- Added protection against BREACH attacks targeting the CSRF token field generated by :doc:`Form Helper <helpers/form_helper>` function :php:func:`form_open()`.