{"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":0.07485,"slug":"CVE-2026-49215","body":"## Overview\n\n### Description\n\nWhen 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.\n\nThe `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.\n\nIn 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.\n\n### Resolution\n\n`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.\n\nThe patch for this issue is available [here](https://github.com/symfony/ux/commit/aed7493db2b4b7bf1f9c79b33cda544f06904b27) for branch 2.x (and forward-ported to 3.x).\n\n### Credits\n\nSymfony would like to thank Anthropic (via Project Glasswing) for reporting the issue and Hugo Alliaume for providing the fix.\n\n## Affected packages\n\n- `symfony/ux-live-component >= 2.22.0, < 2.36.0`\n- `symfony/ux-live-component >= 3.0.0, < 3.1.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `symfony/ux-live-component 2.36.0`\n- `symfony/ux-live-component 3.1.0`","depth":"sunlit","depthScore":14,"depthScoreParts":{"impact":13.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}