CVE-2026-49210CWE-79

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

Low · published July 17, 2026

CVSS v4.0
2.3
EPSS
0%
Percentile
26.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
2.3 · LOW
Vector
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
EPSS
0.00338 · 26.0th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-07-17T16:09Z
EPSS history
Timeline
  • 17 JUL 16:09Z
    Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag
    cvelistv5