--------------------------------

**Security fixes**

* ``bleach.clean`` behavior parsing embedded MathML and SVG content
  with RCDATA tags did not match browser behavior and could result in
  a mutation XSS.

  Calls to ``bleach.clean`` with ``strip=False`` and ``math`` or
  ``svg`` tags and one or more of the RCDATA tags ``script``,
  ``noscript``, ``style``, ``noframes``, ``iframe``, ``noembed``, or
  ``xmp`` in the allowed tags whitelist were vulnerable to a mutation
  XSS.

  This security issue was confirmed in Bleach version v3.1.1. Earlier
  versions are likely affected too.

  Anyone using Bleach <=v3.1.1 is encouraged to upgrade.

  https://bugzilla.mozilla.org/show_bug.cgi?id=1621692

**Backwards incompatible changes**

None

**Features**

None

**Bug fixes**

None