What’s Vulnerable › Vulnerabilities

CVE-2026-49212: Symfony UX: LiveComponentHydrator HMAC checksum lacks component and slot binding

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% 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-345

Description

Symfony UX is a JavaScript ecosystem for Symfony. From 2.8.0 until 2.36.0 and 3.1.0, the HMAC computed by Symfony\UX\LiveComponent\LiveComponentHydrator covered only sorted prop key/value pairs and did not include the component name, the slot identifier (props vs propsFromParent), or request context, allowing a signed blob minted for one component or slot to be replayed in another and set a read-only prop on a target component. This issue is fixed in versions 2.36.0 and 3.1.0.

Affected products

• symfony ux: from 2.8.0 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/a224b5af3e2e33ee14ac71356ae0e0877900a81c
• 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-34w5-c283-j9fg

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