CVE-2026-49210: Symfony Ux

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Symfony Ux: from 2.8.0, before 2.36.0 (fixed in 2.36.0); version 3.0.0 only

Published 2026-07-17. Last modified 2026-07-20.