How severe is GHSA-38x5-rcv4-xf7x?

No CVSS score has been assigned to GHSA-38x5-rcv4-xf7x yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-38x5-rcv4-xf7x?

GHSA-38x5-rcv4-xf7x affects the following packages: symfony/ux-live-component (Packagist), symfony/ux-live-component (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-38x5-rcv4-xf7x?

Update symfony/ux-live-component to 2.36.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-38x5-rcv4-xf7x is resolved across your whole dependency graph.

How do I detect GHSA-38x5-rcv4-xf7x in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/ux-live-component, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-38x5-rcv4-xf7x if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-38x5-rcv4-xf7x?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-38x5-rcv4-xf7x can be triaged on real exposure rather than presence alone.

Is GHSA-38x5-rcv4-xf7x actively exploited in the wild?

No public exploit code has been indexed for GHSA-38x5-rcv4-xf7x yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-38x5-rcv4-xf7x?

GHSA-38x5-rcv4-xf7x has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 27th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-38x5-rcv4-xf7x published, and has it been updated?

GHSA-38x5-rcv4-xf7x was published on June 19, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

GHSA-38x5-rcv4-xf7x — symfony/ux-live-component

Fix: symfony/ux@fbc5e9a

GHSA-38x5-rcv4-xf7x is a security vulnerability in symfony/ux-live-component. A fix is available for symfony/ux-live-component — see the affected versions and patch details below.

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

Also known asCVE-2026-49210

Published

Jun 19, 2026

Updated

Sep 10, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Sep 17, 2026 · OSV.dev, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-38x5-rcv4-xf7x.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

2 pkgs affected

🐘symfony/ux-live-component🐘symfony/ux-live-component

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Symfony\UX\LiveComponent\Util\ChildComponentPartialRenderer::createHtml() interpolates the $childTag argument directly into the HTML output as a tag name, without escaping or validation. The value originates from client-controlled JSON (children[id].tag) parsed by LiveComponentSubscriber and propagated through InterceptChildComponentRenderSubscriber, so an attacker who can reach the Live Component endpoint can inject arbitrary HTML, including <script> tags, on any re-render of a Live Component that contains at least one child component.

In the default configuration, the Live Component endpoint is gated by an Accept: application/vnd.live-component+html request-header check that cannot be set cross-origin without a CORS preflight, so the issue is primarily a defense-in-depth gap. It becomes directly exploitable on applications that have relaxed CORS to allow this header from untrusted origins, or that have been pivoted from another same-origin XSS.

Resolution

ChildComponentPartialRenderer now validates $childTag against a strict HTML tag-name regex before interpolating it, and rejects any value that doesn't match. Anything that wouldn't be a valid HTML tag is dropped before reaching the response.

The patch for this issue is available here for branch 2.x (and forward-ported to 3.x).

Credits

Symfony would like to thank Pascal Cescon for reporting the issue and Hugo Alliaume for providing the fix.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/ux-live-component`	≥ 2.8.0&&< 2.36.0	2.36.0`composer require symfony/ux-live-component:^2.36.0`
🐘Packagist	`symfony/ux-live-component`	≥ 3.0.0&&< 3.1.0	3.1.0`composer require symfony/ux-live-component:^3.1.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/ux-live-component, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/ux-live-component to 2.36.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-38x5-rcv4-xf7x is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-38x5-rcv4-xf7x can be triaged on real exposure rather than presence alone.

Tailored to GHSA-38x5-rcv4-xf7x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Description `Symfony\UX\LiveComponent\Util\ChildComponentPartialRenderer::createHtml()` interpolates the `$childTag` argument directly into the HTML output as a tag name, without escaping or validation. The value originates from client-controlled JSON (`children[id].tag`) parsed by `LiveComponentSubscriber` and propagated through `InterceptChildComponentRenderSubscriber`, so an attacker who can reach the Live Component endpoint can inject arbitrary HTML, including `<script>` tags, on any re-render of a Live Component that contains at least one child component. In the default configuratio

O3 Security · Impact-Aware SCA

Is GHSA-38x5-rcv4-xf7x in your dependencies?

O3 Security finds GHSA-38x5-rcv4-xf7x across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works

GHSA-38x5-rcv4-xf7x — symfony/ux-live-component

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

Real-World Exposure

Description

Description

Resolution

Credits

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is GHSA-38x5-rcv4-xf7x in your dependencies?