CVE-2026-49210

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

State: Published
Severity: 2.3 Low
Published: Jul 17, 2026
Updated: Jul 17, 2026
Reserved: May 28, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	2.3 Low	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	GitHub_M

Weaknesses

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Affected Products

Product	Versions
uxsymfony	>= 3.0.0, < 3.1.0Affected >= 2.8.0, < 2.36.0Affected

References

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