Threats Tagged 'cve-2026-59929'

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.

Adr viewer's Mistune markdown renderer has a URL scheme allowlist gap in its safe_url filter. The filter blocks only four harmful schemes (javascript:, vbscript:, file:, data:) but misses several legacy and chained schemes that can lead to JavaScript execution in some browsers. This allows attacker-controlled URLs with schemes like feed:, livescript:, view-source:, jar:, ms-its:, mk:@MSITStore:, and others to bypass filtering and potentially execute JavaScript when clicked in vulnerable user agents. The vulnerability affects multiple versions of adr-viewer and has a CVSS score of 6.1 (medium severity). A patch is available to address this issue.

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:, and res: to reach rendered href and src attributes and potentially execute script in affected user agents. This issue is fixed in version 3.3.0.