Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M

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

Medium 6.9

In plain English

A medium-severity insufficient verification of data authenticity in ux from symfony. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.9Medium

Exploit odds (30 days)0.2%top 84.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	symfony/ux-live-component	2.36.0	GHSA-34w5-c283-j9fg
Packagist	symfony/ux-live-component	3.1.0	GHSA-34w5-c283-j9fg

Affected products (as reported)

Vendor	Product	Versions
symfony	ux	>= 3.0.0, < 3.1.0< 2.36.0

Weakness: CWE-345 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

References

https://github.com/symfony/ux/security/advisories/GHSA-34w5-c283-j9fg x_refsource_CONFIRM
https://github.com/symfony/ux/commit/a224b5af3e2e33ee14ac71356ae0e0877900a81c x_refsource_MISC
https://github.com/symfony/ux/releases/tag/v2.36.0 x_refsource_MISC
https://github.com/symfony/ux/releases/tag/v3.1.0 x_refsource_MISC