CVE-2023-50262

Dompdf is an HTML to PDF converter for PHP. When parsing SVG images Dompdf
performs an initial validation to ensure that paths within the SVG are
allowed. One of the validations is that the SVG document does not reference
itself. However, prior to version 2.0.4, a recursive chained using two or
more SVG documents is not correctly validated. Depending on the system
configuration and attack pattern this could exhaust the memory available to
the executing process and/or to the server itself. php-svg-lib, when run in
isolation, does not support SVG references for image elements. However,
when used in combination with Dompdf, php-svg-lib will process SVG images
referenced by an image element. Dompdf currently includes validation to
prevent self-referential image references, but a chained reference is not
checked. A malicious actor may thus trigger infinite recursion by chaining
references between two or more SVG images. When Dompdf parses a malicious
payload, it will crash due after exceeding the allowed execution time or
memory usage. An attacker sending multiple request to a system can
potentially cause resource exhaustion to the point that the system is
unable to handle incoming request. Version 2.0.4 contains a fix for this
issue.