Medium severity · published Jul 17, 2026
CVE-2026-49210
Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag
6.1
CVSS
0.3%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UX
ux · symfony
>= 3.0.0, < 3.1.0; >= 2.8.0, < 2.36.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49210
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49210
Patch
https://github.com/symfony/ux/commit/fbc5e9a1bda7e4556be21bb1d970f382760ed9a9
Release Notes
https://github.com/symfony/ux/releases/tag/v2.36.0
Release Notes
https://github.com/symfony/ux/releases/tag/v3.1.0
Vendor Advisory
https://github.com/symfony/ux/security/advisories/GHSA-38x5-rcv4-xf7x
More from ux
7.8
CVE-2026-55878
Symfony: Path Traversal in symfony/ux-toolkit Allows Arbitrary File Write and Read via Crafted Recipe Manifest
7.5
CVE-2026-49211
Symfony UX: Information exposure via unescaped LIKE wildcards in EntitySearchUtil
7.5
CVE-2026-49212
Symfony UX: LiveComponentHydrator HMAC checksum lacks component and slot binding
6.5
CVE-2026-49209
Symfony UX: Denial of service in symfony/ux-live-component via unbounded batch action requests
6.1
CVE-2026-55877
Symfony UX: XSS in symfony/ux-icons via unsanitized SVG content in local files and Iconify on-demand responses