CVE-2021-39138: New anonymous user session acts as if it's created with password
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Developers can use the REST API to signup users and also allow users to login anonymously. Prior to version 4.5.1, when an anonymous user is first signed up using REST, the server creates session incorrectly. Particularly, the authProvider field in Session class under createdWith shows the user logged in creating a password. If a developer later depends on the createdWith field to provide a different level of access between a password user and anonymous user, the server incorrectly classified the session type as being created with a password. The server does not currently use createdWith to make decisions about internal functions, so if a developer is not using createdWith directly, they are not affected. The vulnerability only affects users who depend on createdWith by using it directly. The issue is patched in Parse Server version 4.5.1. As a workaround, do not use the createdWith Session field to make decisions if one allows anonymous login.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Parse Serverto a version that resolves this vulnerability.Fixed in 4.5.1 - Configuration
Update application logic to not make authorization/access-level decisions based on the `_Session` field `createdWith` (including `authProvider`) when anonymous login is permitted; the server may incorrectly classify anonymous sessions as `createdWith: password` prior to 4.5.1.
Application code using Parse Server sessions _Session.createdWith/authProvider = Do not use createdWith (authProvider) for access decisions when anonymous login is allowed
Event History
Frequently Asked Questions
What is CVE-2021-39138?
CVE-2021-39138 is a vulnerability in Parse Server that allows for anonymous user session hijacking.
How can I be affected by CVE-2021-39138?
If you are using Parse Server version up to and excluding 4.5.1, you are affected by CVE-2021-39138.
What is the severity of CVE-2021-39138?
CVE-2021-39138 has a severity rating of medium, with a CVSS score of 6.5.
How do I fix CVE-2021-39138?
To fix CVE-2021-39138, update Parse Server to version 4.5.1 or later.
Where can I find more information about CVE-2021-39138?
You can find more information about CVE-2021-39138 in the references: [link1], [link2], [link3].