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CVE-2026-44896— Mistune: XSS via unescaped figclass/figwidth in Figure directive

Quick assessment

Affected
lepture mistune
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

mistune是Hsiaoming Yang个人开发者的一个快速而强大的 Python Markdown 解析器。 mistune 3.2.0及之前版本存在跨站脚本漏洞，该漏洞源于在src/mistune/directives/image.py中，render_figure()函数将figclass和figwidth选项直接拼接至HTML属性而未进行转义，即使HTMLRenderer(escape=True)启用时也可导致属性注入和跨站脚本攻击。

AI Predicted 6.1 Difficulty: Moderate EPSS 0.20% · P10

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 1

VendorProduct Version RangeStatus
lepture mistune < 3.2.1 affected
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I. Basic Information for CVE-2026-44896

Vulnerability Information
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Vulnerability Title
Mistune: XSS via unescaped figclass/figwidth in Figure directive
Source: CVE Program / CVE List V5
Vulnerability Description
Mistune is a Python Markdown parser with renderers and plugins. In 3.2.0 and earlier, in src/mistune/directives/image.py, the render_figure() function concatenates figclass and figwidth options directly into HTML attributes without escaping. This allows attribute injection and XSS even when HTMLRenderer(escape=True) is used, because these values bypass the inline renderer. Version 3.2.1 contains a patch.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
mistune 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
mistune是Hsiaoming Yang个人开发者的一个快速而强大的 Python Markdown 解析器。 mistune 3.2.0及之前版本存在跨站脚本漏洞，该漏洞源于在src/mistune/directives/image.py中，render_figure()函数将figclass和figwidth选项直接拼接至HTML属性而未进行转义，即使HTMLRenderer(escape=True)启用时也可导致属性注入和跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
lepture mistune < 3.2.1 -

II. Public POCs for CVE-2026-44896

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III. Intelligence Information for CVE-2026-44896

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Patches & Fixes for CVE-2026-44896 (1)

Vendor Advisories for CVE-2026-44896 (1)

Same Patch Batch · lepture · 2026-05-26 · 5 CVEs total

CVE-2026-44898 6.1 MEDIUM Mistune TOC Anchor Injection XSS
CVE-2026-44897 6.1 MEDIUM Mistune Heading ID Attribute Injection XSS
CVE-2026-44708 6.1 MEDIUM Mistune Math Plugin XSS Escape Bypass
CVE-2026-44899 4.7 MEDIUM Mistune Image Directive CSS Injection Vulnerability

IV. Related Vulnerabilities

Same product: mistune
Same vendor: lepture
Same weakness: CWE-79

V. Comments for CVE-2026-44896

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