symfony/ux-live-component: CSRF Protection Bypass — Accept Header is CORS-Safelisted

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.1 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-49215: 0.18% estimated exploitation activity in the next 30 days; percentile 7.28 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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, 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…

Published by the source

19 Jun 2026, 19:35 UTC

Last modified by the source

19 Jun 2026, 19:35 UTC

Source last checked

26 Oct 2026, 14:49 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4m4j-hmqq-3gxm

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-49215

Advisory: symfony/ux-live-component: CSRF Protection Bypass — Accept Header is CORS-Safelisted
IDs: CVE-2026-49215, GHSA-4m4j-hmqq-3gxm
Record: https://patchnext.com/advisories/cve-2026-49215 (revision 1, source checked 26 Oct 2026, 14:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: symfony/ux-live-component 3.1.0, 2.36.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist symfony/ux-live-component: affected >= 2.22.0, < 2.36.0; >= 3.0.0, < 3.1.0; fixed in 3.1.0, 2.36.0

## Suggested inspection (read-only)
- Packagist symfony/ux-live-component: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on symfony/ux-live-component.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4m4j-hmqq-3gxm (GitHub-reviewed advisory GHSA-4m4j-hmqq-3gxm lists affected ranges: Packagist symfony/ux-live-component >=2.22.0 =3.0.0 <3.1.0)

Commands are suggestions: review each one before running it.