---
id: CVE-2026-49215
title: >-
  symfony/ux-live-component: CSRF Protection Bypass — Accept Header is
  CORS-Safelisted
summary: >-
  symfony/ux-live-component: CSRF Protection Bypass — Accept Header is
  CORS-Safelisted
severity: low
cwe:
  - CWE-352
vendor: symfony
product: symfony/ux-live-component
affected:
  - 'symfony/ux-live-component >= 2.22.0, < 2.36.0'
  - 'symfony/ux-live-component >= 3.0.0, < 3.1.0'
patched:
  - symfony/ux-live-component 2.36.0
  - symfony/ux-live-component 3.1.0
published: '2026-06-19'
updated: '2026-06-19'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-4m4j-hmqq-3gxm'
references:
  - url: 'https://github.com/symfony/ux/security/advisories/GHSA-4m4j-hmqq-3gxm'
  - url: >-
      https://github.com/symfony/ux/commit/aed7493db2b4b7bf1f9c79b33cda544f06904b27
  - url: >-
      https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/ux-live-component/CVE-2026-49215.yaml
  - url: 'https://github.com/advisories/GHSA-4m4j-hmqq-3gxm'
tags:
  - ghsa
  - composer
ingestedAt: '2026-06-22T15:52:21.062Z'
ecosystem: composer
epss: 0.00177
epssPercentile: 0.06459
---

## Overview

### Description

When using `symfony/ux-live-component`, methods annotated with `#[LiveAction]` are invokable from the browser and mutate server-side state via AJAX. `Symfony\UX\LiveComponent\EventListener\LiveComponentSubscriber::isLiveComponentRequest()` gated these invocations on the presence of `Accept: application/vnd.live-component+html`, with a code comment stating that this acted as a CSRF protection.

The `Accept` header is a [CORS-safelisted request header](https://fetch.spec.whatwg.org/#cors-safelisted-request-header), so a cross-origin `fetch()` can set it without triggering a preflight. The header therefore provided no CSRF protection. Any `#[LiveAction]` could be forged cross-origin against a victim's session.

In practice the attack is mitigated by `SameSite=Lax` session cookies (Symfony's default), but applications using `SameSite=None`, `credentials: 'include'` with a permissive cookie policy, or that have been pivoted from another same-origin vector remained exposed.

### Resolution

`isLiveComponentRequest()` now additionally requires the request header `X-Requested-With: XMLHttpRequest`. This header is **not** CORS-safelisted, so the browser issues a preflight `OPTIONS` request for any cross-origin attempt; Symfony does not advertise CORS for LiveComponent endpoints, the preflight fails, and the real request is blocked before it reaches the application. The bundled Stimulus client already sends `X-Requested-With` on every LiveComponent request (`RequestBuilder.ts`), so standard usage is unaffected. Cross-origin callers must add `X-Requested-With` to their CORS `Access-Control-Allow-Headers` allow-list.

The patch for this issue is available [here](https://github.com/symfony/ux/commit/aed7493db2b4b7bf1f9c79b33cda544f06904b27) for branch 2.x (and forward-ported to 3.x).

### Credits

Symfony would like to thank Anthropic (via Project Glasswing) for reporting the issue and Hugo Alliaume for providing the fix.

## Affected packages

- `symfony/ux-live-component >= 2.22.0, < 2.36.0`
- `symfony/ux-live-component >= 3.0.0, < 3.1.0`

## Remediation

Upgrade to a patched release:

- `symfony/ux-live-component 2.36.0`
- `symfony/ux-live-component 3.1.0`