Mistune Image Directive CSS Injection Vulnerability (lepture mistune)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.23 % · percentile 14 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
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.
Weaknesses (CWE)
- CWE-79 — Improper Neutralization of Input During Web Page Generation
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 4.7 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N | GitHub_M |
| CVSS 3.1 | MEDIUM 4.7 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-ccfx-mfmx-2fx9 — Mistune Image Directive CSS Injection Vulnerability
- PYSEC-2026-2209 — 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 reg
European references
- ENISA EUVD · EUVD-2026-31992
- GCVE · GCVE-0-2026-44899
CERT-FR advisories
- CERTFR-2026-AVI-0685 — Multiples vulnérabilités dans Microsoft Azure Linux · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*< 3.2.1
Affected products
| Product | Versions |
|---|---|
| lepture · mistune | affected < 3.2.1 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |