CVE-2026-33409

Workarounds

Set allowExpiredAuthDataToken to false (the default) or remove the option from the server configuration.

An authentication bypass vulnerability allows an attacker to log in as any user who has linked a third-party authentication provider, without knowing the user's credentials. The attacker only needs to know the user's provider ID to gain full access to their account, including a valid session token.

This affects Parse Server deployments where the server option allowExpiredAuthDataToken is set to true. The default value is false.

The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.

CVE-2026-33409 has a CVSS score of 9.1 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.6.0-alpha.41, 8.6.52); upgrading removes the vulnerable code path.

Kodem intelligence

Auth providers are now always validated on login, regardless of the allowExpiredAuthDataToken setting. The option allowExpiredAuthDataToken has been deprecated and will be removed in a future major version.

1. What is CVE-2026-33409? CVE-2026-33409 is a high-severity improper authentication vulnerability in parse-server (npm), affecting versions >= 9.0.0, < 9.6.0-alpha.41. It is fixed in 9.6.0-alpha.41, 8.6.52. The application does not adequately verify the identity of a user, device, or process before granting access.
2. How severe is CVE-2026-33409? CVE-2026-33409 has a CVSS score of 9.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of parse-server are affected by CVE-2026-33409? parse-server (npm) versions >= 9.0.0, < 9.6.0-alpha.41 is affected.
4. Is there a fix for CVE-2026-33409? Yes. CVE-2026-33409 is fixed in 9.6.0-alpha.41, 8.6.52. Upgrade to this version or later.
5. Is CVE-2026-33409 exploitable, and should I be worried? Whether CVE-2026-33409 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
6. What actually determines whether CVE-2026-33409 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.
7. How do I fix CVE-2026-33409?
   • Upgrade parse-server to 9.6.0-alpha.41 or later
   • Upgrade parse-server to 8.6.52 or later