VulnerabilityAnalyzed

CVE-2026-49210

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…

LOW 2.3EPSS 0.34%

Does this matter?

Lower severity and a low EPSS score (0.34%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 4.0: 2.3 LOWCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.34% probability · 27th percentile
CISA KEV: Not listed
Weakness: CWE-79
Affected: symfony/ux
Source: security-advisories@github.com

References

https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9Patch
https://github.com/symfony/ux/releases/tag/v2.36.0Release Notes
https://github.com/symfony/ux/releases/tag/v3.1.0Release Notes
https://github.com/symfony/ux/security/advisories/GHSA-38x5-rcv4-xf7xVendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.