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
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-79"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49210.json"
}{
"cpe": [
"cpe:2.3:a:symfony:ux:*:*:*:*:*:*:*:*",
"cpe:2.3:a:symfony:ux:3.0.0:*:*:*:*:*:*:*"
],
"extracted_events": [
{
"introduced": "2.8.0"
},
{
"fixed": "2.36.0"
},
{
"introduced": "3.0.0"
},
{
"last_affected": "3.0.0"
}
],
"source": [
"CPE_RANGE",
"CPE_STRING",
"REFERENCES"
]
}