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.
References
| Link | Resource |
|---|---|
| https://github.com/lepture/mistune/releases/tag/v3.2.1 | Product Release Notes |
| https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9 | Exploit Vendor Advisory |
| https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9 | Exploit Vendor Advisory |
Configurations
History
28 May 2026, 13:38
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:* | |
| References | () https://github.com/lepture/mistune/releases/tag/v3.2.1 - Product, Release Notes | |
| References | () https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9 - Exploit, Vendor Advisory | |
| First Time |
Mistune Project mistune
Mistune Project |
27 May 2026, 14:16
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9 - |
26 May 2026, 21:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-26 21:16
Updated : 2026-05-28 13:38
NVD link : CVE-2026-44899
Mitre link : CVE-2026-44899
CVE.ORG link : CVE-2026-44899
JSON object : View
Products Affected
mistune_project
- mistune
CWE
CWE-79
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')