[css-easing-1] Add privacy and security considerations section

Author: birtles

css-easing-1/Overview.bs

@@ -416,6 +416,23 @@ defined in [[CSSOM]] with the following additional requirements:
     2.   Otherwise, serialize as <a lt="steps()"
          function>steps(&lt;integer&gt;, &lt;step-position&gt;)</a>.
 
+Privacy and Security Considerations {#priv-sec}
+===================================
+
+This specification does not directly introduce any new capabilities to the
+Web platform but rather provides common definitions that may be referenced by
+other specifications.
+As a result, it does not introduce any new privacy and security concerns.
+
+Specifications referencing the features defined in this specification
+should consider that while easing functions most commonly
+take an [=input progress value=] in the range [0,1]
+and produce an [=output progress value=] in the range [0, 1],
+this is not always the case.
+Applications of easing functions should
+define the behavior for inputs and outputs outside this range
+to ensure they do not introduce new security considerations.
+
 Changes since last publication {#changes}
 ==============================