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CVE-2026-49210— Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag

Quick assessment

Affected
symfony ux
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.

Symfony ux是Symfony组织开源的一个Symfony的JavaScript生态系统。 Symfony UX 2.8.0版本至2.36.0之前版本和3.0.0版本至3.1.0之前版本存在跨站脚本漏洞，该漏洞源于ChildComponentPartialRenderer::createHtml()将客户端控制的children[id].tag值直接插入HTML标签名而未进行转义或验证，可能导致在包含至少一个子组件的Live组件重渲染时注入任意HTML，包括<script>标签。

AI Predicted 7.5 Difficulty: Easy EPSS 0.34% · P27

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 2

VendorProduct Version RangeStatus
symfony ux >= 3.0.0, < 3.1.0 affected
>= 2.8.0, < 2.36.0 affected
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I. Basic Information for CVE-2026-49210

Vulnerability Information
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Vulnerability Title
Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag
Source: CVE Program / CVE List V5
Vulnerability Description
Symfony UX is a JavaScript ecosystem for Symfony. From 2.8.0 until 2.36.0 and 3.1.0, Symfony\UX\LiveComponent\Util\ChildComponentPartialRenderer::createHtml() interpolates the client-controlled children[id].tag value from LiveComponentSubscriber and InterceptChildComponentRenderSubscriber directly into HTML as a tag name without escaping or validation, allowing arbitrary HTML, including <script> tags, on any Live Component re-render that contains at least one child component. This issue is fixed in versions 2.36.0 and 3.1.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/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
Symfony UX 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Symfony ux是Symfony组织开源的一个Symfony的JavaScript生态系统。 Symfony UX 2.8.0版本至2.36.0之前版本和3.0.0版本至3.1.0之前版本存在跨站脚本漏洞，该漏洞源于ChildComponentPartialRenderer::createHtml()将客户端控制的children[id].tag值直接插入HTML标签名而未进行转义或验证，可能导致在包含至少一个子组件的Live组件重渲染时注入任意HTML，包括<script>标签。
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
symfony ux >= 3.0.0, < 3.1.0 -

II. Public POCs for CVE-2026-49210

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III. Intelligence Information for CVE-2026-49210

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Patches & Fixes for CVE-2026-49210 (3)

Vendor Advisories for CVE-2026-49210 (1)

Same Patch Batch · symfony · 2026-07-17 · 7 CVEs total

CVE-2026-49209 Symfony UX: Denial of service in symfony/ux-live-component via unbounded batch action requ
CVE-2026-49215 Symfony UX: CSRF Protection Bypass in symfony/ux-live-component — Accept Header is CORS-Sa
CVE-2026-49208 Symfony UX: Format-less date LiveProps parsed with the permissive DateTime constructor
CVE-2026-49212 Symfony UX: LiveComponentHydrator HMAC checksum lacks component and slot binding
CVE-2026-49216 Symfony UX: XSS in symfony/ux-autocomplete via unescaped AJAX response data
CVE-2026-49211 Symfony UX: Information exposure via unescaped LIKE wildcards in EntitySearchUtil

IV. Related Vulnerabilities

Same product: ux
Same vendor: symfony
Same weakness: CWE-79

V. Comments for CVE-2026-49210

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