svglib 2.3.0

Security

• External <image>/<use> references can no longer escape the document's own
  directory. xlink_href_target() joined the reference onto the source
  directory and only checked os.access(), so an absolute reference discarded
  that directory and .. climbed above it, letting an untrusted SVG name any
  file the process could read (CWE-22, GHSA-2p5c-8vcc-4rcw). Absolute
  references are now refused, and the new opt-in external_reference_root on
  svg2rlg()/SvgRenderer confines resolution to a trusted directory,
  propagated into nested external-SVG renderers. Relative references, including
  .., keep working by default.

• The svg2pdf command line tool now sets external_reference_root to the
  input file's own directory, since a file converted from the command line is
  routinely one the user did not author. Pass -R/--external-root with a
  parent directory to allow shared assets, or / to allow any relative
  reference. Library callers are unaffected: the default stays None.