CVE-2026-33409: Parse Server Authentication Bypass via Partial AuthData
Summary
CVE-2026-33409: Parse Server has an auth provider validation bypass on login via partial authData. Affects parse-server across 2 version ranges.
< 8.6.52
>= 9.0.0, < 9.6.0-alpha.41
Fixed in 8.6.52 or 9.6.0-alpha.41, depending on the release line you run. How to fix ↓
Also tracked for
- parse · Bitnami
The same CVE-2026-33409 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Parse Server is an open-source backend framework that allows developers to build applications with a robust server-side infrastructure. It provides features such as data storage, user authentication, and real-time notifications. However, certain configurations can expose it to security vulnerabilities, including the recent authentication bypass issue.
Vulnerability Detail
The vulnerability arises from an authentication bypass that allows attackers to log in as any user linked to a third-party authentication provider without needing the user's credentials. By knowing the user's provider ID, an attacker can gain full access to the user's account, including a valid session token. This issue primarily affects Parse Server deployments where the 'allowExpiredAuthDataToken' option is set to true, which is not the default setting.
How To Fix
Latest published version: 9.10.5 as of 22 Oct 2026
npm install parse-server@9.10.5Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 8.6.528.6.52npm install parse-server@8.6.52 -
>= 9.0.0, < 9.6.0-alpha.419.6.0-alpha.41npm install parse-server@9.6.0-alpha.41
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
As a temporary workaround, ensure that the 'allowExpiredAuthDataToken' option is set to false in your server configuration. This can be done by modifying your server settings as follows: 'allowExpiredAuthDataToken: false'.
Conclusion
The authentication bypass vulnerability in Parse Server poses a significant risk to user accounts linked to third-party authentication providers. It is crucial to update to the patched versions or implement the recommended workaround to mitigate this risk.
See every vulnerability recorded for parse-server →
FAQ
The vulnerability allows attackers to bypass authentication and access user accounts without knowing the user's credentials.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
If immediate updates are not possible, ensure that 'allowExpiredAuthDataToken' is set to false as a temporary measure.
Versions 9.0.0 to 9.6.0-alpha.40 and all versions below 8.6.52 are affected by this vulnerability.
The CVSS score for this vulnerability is 7.0, indicating a high severity level.
References
Related vulnerabilities
Recent vulnerabilities recorded for parse-server.
