Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
AV AC PR UI S C I A CVSS EPSS %ile KEV N L N R C L L N 6.1 .0023 13.8 —
AFFECTED Product Versions Fixed mistune < 3.2.1 – —
TIMELINE May 7 Reserved by GitHub_M May 26 EXPLOIT PUBLISHED — CVE-2026-44899 (lepture mistune). Public exploit reference added. May 26 Published (CNA: GitHub_M)
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, the Image directive plugin validates the :width: and :height: options with a regex compiled as _num_re = re.compile(r"^\d+(?:\.\d*)?"). When the validated value is not a plain integer, render_block_image() inserts it directly into a style="width:...;" or style="height:...;" attribute. Because the value was accepted by the prefix-only regex, any CSS after the leading digits reaches the style= attribute verbatim and without escaping. This vulnerability is fixed in 3.2.1.
| Date | Event | Detail |
|---|---|---|
| May 7, 2026 | Reserved | Reserved by GitHub_M |
| May 26, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-44899 (lepture mistune). Public exploit reference added. |
| May 26, 2026 | Published | Published (CNA: GitHub_M) |
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|---|---|---|---|
| lepture | mistune | — | < 3.2.1 | — |
Authoritative record: CVE-2026-44899 at cve.org
Vendors: lepture
Weaknesses: CWE-79
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-44899 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.