What’s Vulnerable › Vulnerabilities

CVE-2026-49209: Symfony UX: Denial of service in symfony/ux-live-component via unbounded batch action requests

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-17 · updated 2026-10-24
• Weakness: CWE-770

Description

Symfony UX is a JavaScript ecosystem for Symfony. From 2.5.0 until 2.36.0 and 3.1.0, Symfony\UX\LiveComponent\Controller\BatchActionController::__invoke() iterates over the client-supplied actions array and issues a full HttpKernel sub-request for each entry; because the array size is never bounded, an authenticated client can submit a single _batch request containing thousands of actions and exhaust CPU, memory, and database connections on the application server. This issue is fixed in versions 2.36.0 and 3.1.0.

Affected products

• symfony ux: from 2.5.0 before 2.36.0; 3.0.0 — fixed in 2.36.0

How to fix

Upgrade to a fixed version: symfony ux 2.36.0. Check the vendor advisory for mitigations.

References

• https://github.com/symfony/ux/commit/95e878d5257f13d6d652ca95e3ef6bb0934d674f
• https://github.com/symfony/ux/releases/tag/v2.36.0
• https://github.com/symfony/ux/releases/tag/v3.1.0
• https://github.com/symfony/ux/security/advisories/GHSA-mm82-c99c-h2cf

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