Threats Tagged 'cve-2026-59928'

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.

CVE-2026-59928 is a high-severity algorithmic-complexity denial-of-service vulnerability in the adr-viewer product's use of the Mistune markdown parser. The vulnerability arises from quadratic-time parsing behavior in the reference-link definition handling code, causing CPU usage to increase quadratically with the number of repeated or distinct reference-link definitions in markdown input. This can be exploited by an attacker submitting specially crafted markdown documents with many repeated reference-link definitions, leading to significant CPU resource exhaustion during parsing. A patch is available that changes the parsing logic to linear time by amortizing the scanning of definitions.

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.