Executive brief
Symfony UX is a collection of tools for building interactive user interfaces in Symfony applications. A security flaw in the LiveComponent library could allow an attacker to bypass data integrity checks by reusing security tokens from one part of the application in another. This could potentially allow unauthorized changes to data fields that were intended to be read-only, affecting the integrity of the application's state.
Technical details
A vulnerability exists in Symfony\UX\LiveComponent\LiveComponentHydrator where the HMAC checksum computed for data integrity only covers sorted property key/value pairs. It fails to include the component name, slot identifier (e.g., 'props' vs 'propsFromParent'), or request context in the signature. An attacker can exploit this by taking a valid signed blob from one component or slot and replaying it in another, potentially allowing them to set or overwrite read-only properties on a target component. The issue is addressed by binding the HMAC checksum to the component name and slot in versions 2.36.0 and 3.1.0.
Affected products
- symfony ux >= 2.8.0, < 2.36.0
- symfony ux >= 3.0.0, < 3.1.0
Timeline
- 2026-05-24: patched: Fix committed to repository
- 2026-05-29: advisory: Release v2.36.0 and v3.1.0 published
- 2026-07-17: disclosed: CVE published to NVD