Vulnerability in Symfony Ux

CVE-2026-49212

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.002 (14.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 14.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-49212: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Symfony Ux — versions >= 3.0.0, < 3.1.0, < 2.36.0, 3.0.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-49212?
CVE-2026-49212 is a high-severity vulnerability in Symfony Ux, classified under Insufficient Verification of Data Authenticity. CVSS score: 7.5/10. Published 2026-07-17.
How severe is CVE-2026-49212?
High severity. CVSS v3 base score is 7.5 out of 10.