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CVE-2026-8630— justhtml before 1.12.0 Mutation XSS via Raw Text Elements

Quick assessment

Affected
EmilStenstrom justhtml
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.

justhtml 在 1.12.0 之前的版本（即版本 <= 1.11.0）在处理原始文本元素（如 和 ）的序列化时，存在一个变异型跨站脚本（mXSS）漏洞。当 函数使用保留这些元素的自定义策略处理 DOM 树时，这些元素内部的文本节点会以未转义的方式原样序列化。这使得攻击者可以构造包含匹配闭合标签序列的受控文本，从而突破原始文本上下文，并在序列化输出中注入任意 HTML。由于默认的清理策略会丢弃 和 元素的内容，因此默认清理策略不受此漏洞影响。

CVSS 6.1 · Medium EPSS 0.19% · P8

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-2026-8630

Vulnerability Information
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Vulnerability Title
justhtml before 1.12.0 Mutation XSS via Raw Text Elements
Source: CVE Program / CVE List V5
Vulnerability Description
justhtml before 1.12.0 (versions <= 1.11.0) contains a mutation cross-site scripting (mXSS) vulnerability in the serialization of raw-text elements such as <style> and <script>. When a DOM tree is processed by sanitize_dom() using a custom policy that keeps these elements, text nodes inside them are serialized literally without escaping, allowing attacker-controlled text containing the matching closing tag sequence to break out of the raw-text context and inject arbitrary HTML into the serialized output. The default sanitization policy is not affected because it drops the contents of style and script.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A: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

Affected Products

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

II. Public POCs for CVE-2026-8630

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III. Intelligence Information for CVE-2026-8630

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Vendor Advisories for CVE-2026-8630 (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-2026-8445 9.8 CRITICAL justhtml before 1.12.0 Sanitizer Bypass via Markdown
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-2026-5751 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-2026-8630

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