Summary
Overview
The Auth0 PHP SDK contains a 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.
Am I Affected?
You are affected by this vulnerability if you meet the following preconditions:
- Applications using the Auth0-PHP SDK, versions between 8.0.0-BETA3 to 8.3.0.
- Applications using the following SDKs that rely on the Auth0-PHP SDK versions between 8.0.0-BETA3 to 8.3.0:
a. Auth0/symfony,
b. Auth0/laravel-auth0,
c. Auth0/wordpress.
Fix
Upgrade Auth0/Auth0-PHP to 8.3.1.
Acknowledgement
Okta would like to thank Andreas Forsblom for discovering this vulnerability.
Impact
Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2025-48951? CVE-2025-48951 is a critical-severity insecure deserialization vulnerability in auth0/auth0-php (composer), affecting versions >= 8.0.0-BETA3, < 8.3.1. It is fixed in 8.3.1. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
- Which versions of auth0/auth0-php are affected by CVE-2025-48951? auth0/auth0-php (composer) versions >= 8.0.0-BETA3, < 8.3.1 is affected.
- Is there a fix for CVE-2025-48951? Yes. CVE-2025-48951 is fixed in 8.3.1. Upgrade to this version or later.
- Is CVE-2025-48951 exploitable, and should I be worried? Whether CVE-2025-48951 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-48951 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-48951? Upgrade
auth0/auth0-phpto 8.3.1 or later.