Deserialization of Untrusted Data in Auth0 Symfony SDK CVE-2025-48951 - Jun 3, 2025

Description

The Auth0 Symfony SDK contains a critical vulnerability due to insecure deserialization of cookie data. If exploited, since SDKs process cookie content without prior authentication, a threat actor could send a specially crafted cookie containing malicious serialized data.

Affected versions

You are affected if you meet the following preconditions:

Applications using the Auth0 Symfony SDK, versions between 5.0.0 BETA-0 to 5.0.0.
Auth0 Symfony SDK uses the Auth0-PHP SDK with version 8.0.0-BETA3 to 8.3.0.

Fix

Upgrade Auth0/symfony to version 5.4.0.

Acknowledgement

Okta would like to thank Andreas Forsblom for their discovery.

CVE details

CVE ID	CVE-2025-48951
Published Date	2025-06-03
Vulnerability Type	Deserialization of Untrusted Data
CWE	CWE-502 - Deserialization of Untrusted Data
CVSS v4	Score: 9.3 Vector string: https://www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:H

References

Deserialization of Untrusted Data in Auth0 Symfony SDK