WeasyPrint vulnerabilities

In WeasyPrint prior to 70.0, server-side applications that configure a restrictive url_fetcher and pass attacker-influenced values to HTML.write_pdf() can have the restriction bypassed through the xmp_metadata or stylesheets options. In weasyprint/pdf/init.py, xmp_metadata calls select_source() without the document url_fetcher, allowing an accessible local file to be read and embedded verbatim in the output PDF. In weasyprint/document.py, stylesheets constructs CSS() without the document url_fetcher, allowing local or internal resource loading and propagating the permissive fetcher through nested CSS imports and url() references. The stylesheets channel applies fetched resources but does not by itself disclose stylesheet comments verbatim.

WeasyPrint before 69.0 embeds unescaped HTML presentational-hint attribute values into CSS in weasyprint/css/__init__.py when presentational_hints=True. The background attribute is inserted into a background-image:url() declaration and parsed by tinycss2.parse_blocks_contents(), allowing untrusted HTML to inject additional CSS declarations. Applications that render untrusted HTML with presentational hints enabled can be affected by CSS injection and server-side requests through injected url() values.

In WeasyPrint prior to version 68.0, a server-side request forgery (SSRF) protection bypass exists in the default `url_fetcher`. Even if a developer implements a custom `url_fetcher` to block access to internal resources, an attacker can bypass this protection because the underlying `urllib` library automatically follows HTTP redirects without re-validating the new destination against the security policy.