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CVE-2026-49215 medium CVSS 5.4

Cross-Site Request Forgery (CSRF) in symfony/ux-live-component (CVE-2026-49215)

Summary

Vulnerability in symfony/ux-live-component (CVE-2026-49215). Risk of unauthorized operations or information disclosure. Exploitable via Accept. Mitigation: upgrade to 3.1.0 or later.

Original description

The description as published by the source.

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 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 (`RequestBui…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-49215 has been found in symfony/ux-live-component.
Attackers can target a specific entry point like Accept over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade symfony/ux-live-component to 3.1.0 or later.
If unsure, ask your IT team or search "symfony/ux-live-component CVE-2026-49215" on the vendor's site.

CVE-2026-49215 (symfony/ux-live-component) — CWE-352 / CVSS v3 5.4
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: Accept / OPTIONS / RequestBuilder.ts
Patched: 3.1.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

CSRF (CWE-352) exists in symfony/ux-live-component. Attackers reach the vulnerable code path via Accept without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of symfony/ux-live-component. Attack surface: Accept / OPTIONS / RequestBuilder.ts.

🔥 Severity

Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.1.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'symfony/ux-live-component' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'symfony/ux-live-component' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で symfony/ux-live-component を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade symfony/ux-live-component to 3.1.0

    ステージング環境で 3.1.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

composer symfony/ux-live-component
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.0"}]}]
Packagist symfony/ux-live-component
[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"fixed":"3.1.0"}]}]

References

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