CVE-2026-33538: Parse Server: Denial of service via unindexed database query for unconfigured auth providers
Impact
An unauthenticated attacker can cause Denial of Service by sending authentication requests with arbitrary, unconfigured provider names. The server executes a database query for each unconfigured provider before rejecting the request, and since no database index exists for unconfigured providers, each request triggers a full collection scan on the user database. This can be parallelized to saturate database resources.
Patches
The fix validates that an authentication provider is configured before executing any database query. Requests with unconfigured providers are now rejected immediately without querying the database.
Workarounds
There is no known workaround other than upgrading.
Other sources
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.58 and 9.6.0-alpha.52, an unauthenticated attacker can cause denial of service by sending authentication requests with arbitrary, unconfigured provider names. The server executes a database query for each unconfigured provider before rejecting the request, and since no database index exists for unconfigured providers, each request triggers a full collection scan on the user database. This can be parallelized to saturate database resources. This issue has been patched in versions 8.6.58 and 9.6.0-alpha.52.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33538?
CVE-2026-33538 is classified as a denial of service vulnerability that can be exploited by unauthenticated attackers.
How does CVE-2026-33538 affect Parse Server?
CVE-2026-33538 allows attackers to cause a denial of service by executing unindexed database queries when specific authentication providers are not configured.
How do I fix CVE-2026-33538?
To fix CVE-2026-33538, upgrade your Parse Server to versions 8.6.58 or 9.6.0-alpha.52 or later.
What are the affected versions for CVE-2026-33538?
CVE-2026-33538 affects Parse Server versions prior to 8.6.58 and 9.6.0-alpha.52.
Can CVE-2026-33538 be exploited remotely?
Yes, CVE-2026-33538 can be exploited remotely by unauthenticated users.