SecuriTricks - CVE-2026-44899

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.

Product(s) Impacted

Vendor	Product	Versions
Mistune	Mistune	<3.2.1

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	mistune	mistune	<3.2.1	/	/	/	/	/	/

References

https://github.com/lepture/mistune/releases/tag/v3.2.1

https://github.com/lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9

CVSS Score

4.7 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: NONE
Scope: CHANGED
Confidentiality Impact: LOW
Integrity Impact: NONE
Availability Impact: NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

View Vector String

Timeline

Published: May 26, 2026, 9:16 p.m.
Last Modified: May 27, 2026, 7:42 p.m.

Status : Undergoing Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

[email protected]

CVE-2026-44899