CVE-2021-28957	21.03.21 06:15
lxml 4.6.2 places the HTML action attribute into defs.link_attrs (in
html/defs.py) for later use in input sanitization, but does not do the
same for the HTML5 formaction attribute.

Upstream fixed it in 4.6.3 (
https://github.com/lxml/lxml/commit/2d01a1ba8984e0483ce6619b972832377f208a0d
), so we should probably upgrade to that.

Has lots of dependents so I suppose it needs grafting? Is that useful
and does it work for Python packages?

Léo