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

**Security fixes**

* ``bleach.clean`` behavior parsing style attributes could result in a
  regular expression denial of service (ReDoS).

  Calls to ``bleach.clean`` with an allowed tag with an allowed
  ``style`` attribute were vulnerable to ReDoS. For example,
  ``bleach.clean(..., attributes={'a': ['style']})``.

  This issue was confirmed in Bleach versions v3.1.3, v3.1.2, v3.1.1,
  v3.1.0, v3.0.0, v2.1.4, and v2.1.3. Earlier versions used a similar
  regular expression and should be considered vulnerable too.

  Anyone using Bleach <=v3.1.3 is encouraged to upgrade.

  https://bugzilla.mozilla.org/show_bug.cgi?id=1623633

**Backwards incompatible changes**

* Style attributes with dashes, or single or double quoted values are
  cleaned instead of passed through.

**Features**

None

**Bug fixes**

None