Safe Modes

Asciidoctor provides security levels that control the read and write access of attributes, include directives, macros, and scripts while a document is processing. Each level includes the restrictions enabled in the prior security level.

The safe mode can be set from the CLI and the API. You can also enable or disable content based on the current safe mode.


The UNSAFE safe mode level disables any security features enforced by Asciidoctor. Ruby is still subject to its own restrictions.

This is the default safe mode for the CLI. Its integer value is 0.


The SAFE safe mode level prevents access to files which reside outside of the parent directory of the source file. Include directives (include::[]) are enabled, but paths to include files must be within the parent directory. This mode allows assets (such as the stylesheet) to be embedded in the document.

Its integer value is 1.


The SERVER safe mode level disallows the document from setting attributes that would affect conversion of the document. This level trims docfile to its relative path and prevents the document from:

  • setting source-highlighter, doctype, docinfo and backend

  • seeing docdir (as it can reveal information about the host filesystem)

It allows icons and linkcss.

Its integer value is 10.


The SECURE safe mode level disallows the document from attempting to read files from the file system and including their contents into the document. Additionally, it:

  • disables icons

  • disables include directives (include::[])

  • data can not be retrieved from URIs

  • prevents access to stylesheets and JavaScripts

  • sets the backend to html5

  • disables docinfo files

  • disables data-uri

  • disables interactive (opts=interactive) and inline (opts=inline) modes for SVGs

  • disables docdir and docfile (as these can reveal information about the host filesystem)

  • disables source highlighting

Asciidoctor extensions may still embed content into the document depending whether they honor the safe mode setting.

This is the default safe mode for the API. Its integer value is 20.

GitHub processes AsciiDoc files using the SECURE mode.