CVE-2026-49215
CVE-2026-49215 is a Cross-Site Request Forgery (CSRF) vulnerability in symfony/ux-live-component. O3 Security confirms whether CVE-2026-49215 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Symfony UX: CSRF Protection Bypass in symfony/ux-live-component — Accept Header is CORS-Safelisted
Blast Radius
symfony/ux-live-component🐘symfony/ux-live-componentReal-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 is a JavaScript ecosystem for Symfony. From 2.22.0 until 2.36.0 and 3.1.0, Symfony\UX\LiveComponent\EventListener\LiveComponentSubscriber::isLiveComponentRequest() gates #[LiveAction] invocations on Accept: application/vnd.live-component+html, but the Accept header is CORS-safelisted and cross-origin fetch() can set it without preflight, allowing forged cross-origin #[LiveAction] requests against a victim session when applications use SameSite=None, credentials: 'include', a permissive cookie policy, or a same-origin pivot. This issue is fixed in versions 2.36.0 and 3.1.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/ux-live-component | ≥ 2.22.0&&< 2.36.0 | 2.36.0 |
| 🐘Packagist | symfony/ux-live-component | ≥ 3.0.0&&< 3.1.0 | 3.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/ux-live-component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 CVE-2026-49215 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 pinpoints whether CVE-2026-49215 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-49215. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-49215 in your dependencies?
O3 detects CVE-2026-49215 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.