Parse Server has an auth provider validation bypass on login via partial authData
### Impact 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`. ### Patches 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. ### Workarounds Set `allowExpiredAuthDataToken` to `false` (the default) or remove the option from the server configuration.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-33409US | critical9.1 | — | ||
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.52 and 9.6.0-alpha.41, an authentication bypass vulner… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/parse-community/parse-serverPACKAGE
- https://github.com/parse-community/parse-server/commit/8d7df5639c4a35768fe8b78b4580b30e8a74721cWEB
- https://github.com/parse-community/parse-server/commit/98f4ba5bcf2c199bfe6225f672e8edcd08ba732dWEB
- https://github.com/parse-community/parse-server/pull/10246WEB
- https://github.com/parse-community/parse-server/pull/10247WEB
- https://github.com/parse-community/parse-server/security/advisories/GHSA-pfj7-wv7c-22prWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-33409ADVISORY
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