Version 3.12.0 changed xml2rfc so that it would not access local files without the presence of its new --allow-local-file-access flag.
This prevented XML External Entity (XXE) injection attacks with xinclude and XML entity references.

It was discovered that xml2rfc does not respect --allow-local-file-access when a local file is specified as src in artwork or sourcecode elements. Furthermore, XML entity references can include any file inside the source dir and below without using the --allow-local-file-access flag.

The xml2rfc <= 3.26.0 behaviour:

Impact

Anyone running xml2rfc as a service that accepts input from external users is impacted by this issue.
Specifying a file in src attribute in artwork or sourcecode elements will cause the contents of that file to appear in xml2rfc’s output results.
But that file has to be inside the same directory as the XML input source file.
For artwork and sourcecode, xml2rfc will not look above the source file directory.

The proposed new behaviour

• Generalize file access checks.
• Only allow access to files within src dir and below. (xml entity include can access templates dir).
• Always allow access to templates_dir for XML entity includes.

New behaviour:

Workarounds

Use a secure temporary directory to process un-trusted XML files, and do not reuse it for processing other XML documents.