---
id: CVE-2026-115351
title: Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option
summary: >-
  Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that
  allows attackers controlling markdown input to inject arbitrary style
  declarations via the unvalidated figwidth option of the figure directive.
  Attackers can app…
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-94
vendor: lepture
product: mistune
affected:
  - mistune >= 3.2.1 < 3.3.0
published: '2026-10-22'
updated: '2026-10-22'
sourceUpdated: '2026-10-22T19:13:27.678Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-115351'
references:
  - url: 'https://github.com/lepture/mistune/security/advisories/GHSA-xmwc-wjpr-q378'
    label: GitHub Security Advisory (GHSA-xmwc-wjpr-q378)
  - url: >-
      https://www.vulncheck.com/advisories/mistune-3.2.1-before-3.3.0-css-injection-via-figure-directive-figwidth-option
    label: >-
      VulnCheck Advisory: Mistune 3.2.1 before 3.3.0 CSS Injection via Figure
      Directive figwidth Option
tags:
  - cve.org
ingestedAt: '2026-10-22T22:00:50.396Z'
---

## Overview

Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.

## Affected

- `mistune >= 3.2.1 < 3.3.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.