In src/mistune/directives/image.py, the render_figure() function concatenates figclass and figwidth options directly into HTML attributes without escaping (lines 152-168).
This allows attribute injection and XSS even when HTMLRenderer(escape=True) is used, because these values bypass the inline renderer.
Other attributes in the same file (src, alt, style) are properly escaped; figclass/figwidth were missed.
In
src/mistune/directives/image.py, therender_figure()function concatenatesfigclassandfigwidthoptions directly into HTML attributes without escaping (lines 152-168).This allows attribute injection and XSS even when
HTMLRenderer(escape=True)is used, because these values bypass the inline renderer.Other attributes in the same file (src, alt, style) are properly escaped; figclass/figwidth were missed.