Parse Server's custom object ID allows to acquire role privileges

Impact

If the Parse Server option allowCustomObjectId: true is set, an attacker that is allowed to create a new user can set a custom object ID for that new user that exploits the vulnerability and acquires privileges of a specific role.

Patches

Improved validation for custom user object IDs. Session tokens for existing users with an object ID that exploits the vulnerability are now rejected.

Workarounds

• Disable custom object IDs by setting allowCustomObjectId: false or not setting the option which defaults to false.
• Use a Cloud Code Trigger to validate that a new user's object ID doesn't start with the prefix role:.

References

• https://github.com/parse-community/parse-server/security/advisories/GHSA-8xq9-g7ch-35hg
• https://github.com/parse-community/parse-server/pull/9317 (fix for Parse Server 7)
• https://github.com/parse-community/parse-server/pull/9318 (fix for Parse Server 6)