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CVE-2026-8445— justhtml before 1.12.0 Sanitizer Bypass via Markdown

Quick assessment

Affected
EmilStenstrom justhtml
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

justhtml 版本 <= 1.11.0（该问题已在 1.12.0 版本中修复）在通过 将已解析的文档转换为 Markdown 格式时，未能充分转义文本节点中的 HTML 特殊字符（如尖括号）。虽然一部分 Markdown 元字符会被转义，但 和 等字符会被保留。因此，在 中原本安全的不可信输入——包括经过实体解码的文本（例如 ）——以及来自 RCDATA/RAWTEXT 解析元素（如 、 、 和 ）的文本——可能会以原始 HTML 的形式出现在 Markdown 输出中，从而导致绕过安全过滤器，并在这些输出被渲

CVSS 9.8 · Critical

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 2

VendorProduct Version RangeStatus
EmilStenstrom justhtml < 1.12.0 affected
1.12.0 unaffected
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I. Basic Information for CVE-2026-8445

Vulnerability Information
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Vulnerability Title
justhtml before 1.12.0 Sanitizer Bypass via Markdown
Source: CVE Program / CVE List V5
Vulnerability Description
justhtml versions <= 1.11.0 (fixed in 1.12.0) do not sufficiently escape HTML-significant characters (angle brackets) in text nodes when converting a parsed document to Markdown via to_markdown(). While a small set of Markdown metacharacters are escaped, characters such as < and > are preserved, so untrusted input that is safe in to_html() — including entity-decoded text (e.g. &lt;script&gt;) or text from RCDATA/RAWTEXT-parsed elements like <title>, <textarea>, <noscript>, and <plaintext> — can be emitted as raw HTML in the Markdown output, enabling a sanitizer bypass and potential cross-site scripting when that output is rendered.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
EmilStenstrom justhtml 0 ~ 1.12.0 -

II. Public POCs for CVE-2026-8445

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 10481 chars
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Trigger conditions & impact
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III. Intelligence Information for CVE-2026-8445

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Vendor Advisories for CVE-2026-8445 (2)

Same Patch Batch · EmilStenstrom · 2026-08-23 · 11 CVEs total

CVE-2026-7808 9.8 CRITICAL justhtml before 1.16.0 Multiple Security Issues via Sanitization
CVE-2026-5388 9.8 CRITICAL justhtml before 1.15.0 Multiple Security Issues
CVE-2026-9769 7.5 HIGH justhtml before 1.10.0 Denial of Service via deeply nested HTML
CVE-2026-4671 7.5 HIGH justhtml before 1.18.0 Denial of Service via CSS Selector
CVE-2026-77088 6.1 MEDIUM justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span
CVE-2026-74793 6.1 MEDIUM justhtml before 3.11.0 XSS via selectedcontent projection
CVE-2026-6827 6.1 MEDIUM justhtml before 1.17.0 Multiple Cross-Site Scripting Vulnerabilities
CVE-2026-8630 6.1 MEDIUM justhtml before 1.12.0 Mutation XSS via Raw Text Elements
CVE-2026-5751 6.1 MEDIUM justhtml before 1.14.0 Mutation XSS via custom sanitization policies
CVE-2026-5389 6.1 MEDIUM justhtml before 1.13.0 XSS via code fence breakout

IV. Related Vulnerabilities

Same product: justhtml
Same vendor: EmilStenstrom
Same weakness: CWE-79

V. Comments for CVE-2026-8445

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