Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M

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

Low 2.3

In plain English

A low-severity cross-site scripting in ux from symfony. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)2.3Low

Exploit odds (30 days)0.3%top 72.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	symfony/ux-live-component	2.36.0	GHSA-38x5-rcv4-xf7x
Packagist	symfony/ux-live-component	3.1.0	GHSA-38x5-rcv4-xf7x

Affected products (as reported)

Vendor	Product	Versions
symfony	ux	>= 3.0.0, < 3.1.0>= 2.8.0, < 2.36.0

Weakness: CWE-79 · 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

References

https://github.com/symfony/ux/security/advisories/GHSA-38x5-rcv4-xf7x x_refsource_CONFIRM
https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9 x_refsource_MISC
https://github.com/symfony/ux/releases/tag/v2.36.0 x_refsource_MISC
https://github.com/symfony/ux/releases/tag/v3.1.0 x_refsource_MISC