CVE-2026-55850— Element Web: A malicious homeserver can inject HTML in Element Web using its homepage
Quick assessment
Affected
element-hq element-web
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.
Element Web 是一个基于 Matrix React SDK 构建的 Matrix 网页客户端。在版本 1.12.22 之前，EmbeddedPage 组件（位于 apps/web/src/components/structures/EmbeddedPage.tsx）通过 dangerouslySetInnerHTML 直接渲染由主服务器（homeserver）提供的首页内容，且未通过 sanitizedHtmlNode 进行 sanitization（安全净化）。攻击者控制的恶意主服务器可以注入精心构造的
Possible ATT&CK Techniques 1 AI
T1189 · Drive-by CompromiseAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| element-hq | element-web | < 1.12.22 |
affected |
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I. Basic Information for CVE-2026-55850
Vulnerability Information
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Vulnerability Title
Element Web: A malicious homeserver can inject HTML in Element Web using its homepage
Source: CVE Program / CVE List V5
Vulnerability Description
Element Web is a Matrix web client built using the Matrix React SDK. Prior to 1.12.22, EmbeddedPage in apps/web/src/components/structures/EmbeddedPage.tsx renders homeserver-supplied homepage content through dangerouslySetInnerHTML without passing it through sanitizedHtmlNode. A malicious homeserver can provide crafted HTML that Element Web renders on the homepage; the content security policy prevents JavaScript but not phishing HTML. This issue is fixed in version 1.12.22.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/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
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| element-hq | element-web | < 1.12.22 | - |
|
II. Public POCs for CVE-2026-55850
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-55850 (1)
Vendor Advisories for CVE-2026-55850 (1)
Vendor Pages for CVE-2026-55850 (1)
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🔗 Release v1.12.22 · element-hq/element-web · GitHub x_refsource_MISC
Other References for CVE-2026-55850 (1)
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V. Comments for CVE-2026-55850
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