Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-44899

26
FAUCET Score

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.

First published: May 26, 2026Last modified: May 26, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 3.2.1CPE matchmatch criteria
cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.7MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.23%
Probability of exploitation in next 30 days
EPSS Percentile
13.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0023 is in the 14th percentile among its peer group of 26,236 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

microsoftpatch availablevia msrc
Product: azl3 python-mistune 3.0.2-1 on Azure Linux 3.0Fixed in: 3.2.1-1
microsoftpatch availablevia msrc
Product: 21330-17084Fixed in: 3.2.1-1
pippatch availablevia ghsa
Product: mistuneFixed in: 3.2.1
github_advisoryvendor investigatingvia nvd_reference
View patch

Vendor Advisories (2)

pipGHSA-ccfx-mfmx-2fx9medium

Mistune Image Directive CSS Injection Vulnerability

May 14, 2026
microsoft2026-May/CVE-2026-44899Moderate

Mistune Image Directive CSS Injection Vulnerability

May 12, 2026

References

github.com / lepture/mistune/releases/tag/v3.2.1
ProductRelease Notes
github.com / lepture/mistune/security/advisories/GHSA-ccfx-mfmx-2fx9
ExploitVendor Advisory