CVE-2026-30939: Parse Server has Denial of Service (DoS) and Cloud Function Dispatch Bypass via Prototype Chain Resolution
Impact
An unauthenticated attacker can crash the Parse Server process by calling a Cloud Function endpoint with a prototype property name as the function name. The server recurses infinitely, causing a call stack size error that terminates the process.
Other prototype property names bypass Cloud Function dispatch validation and return HTTP 200 responses, even though no such Cloud Functions are defined. The same applies to dot-notation traversal.
All Parse Server deployments that expose the Cloud Function endpoint are affected.
Patches
The internal handler registries for Cloud Functions, Jobs, Triggers, and Validators have been changed to prevent prototype chain properties from being resolved.
Workarounds
Place a reverse proxy or WAF in front of Parse Server and block requests to Object.prototype property names.
References
- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-5j86-7r7m-p8h6 - Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.1-alpha.2 - Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.13
Other sources
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 8.6.13 and 9.5.1-alpha.2, an unauthenticated attacker can crash the Parse Server process by calling a Cloud Function endpoint with a prototype property name as the function name. The server recurses infinitely, causing a call stack size error that terminates the process. Other prototype property names bypass Cloud Function dispatch validation and return HTTP 200 responses, even though no such Cloud Functions are defined. The same applies to dot-notation traversal. All Parse Server deployments that expose the Cloud Function endpoint are affected. This vulnerability is fixed in 8.6.13 and 9.5.1-alpha.2.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-30939?
CVE-2026-30939 has a high severity as it allows unauthenticated attackers to crash the Parse Server process.
How do I fix CVE-2026-30939?
To fix CVE-2026-30939, upgrade to Parse Server version 9.5.1-alpha.2 or 8.6.13.
What types of attacks are possible with CVE-2026-30939?
CVE-2026-30939 allows attackers to exploit prototype property names to induce an infinite recursion, crashing the server.
Which versions of Parse Server are affected by CVE-2026-30939?
Parse Server versions from 9.0.0-alpha.1 up to 9.5.1-alpha.2 and below 8.6.13 are affected by CVE-2026-30939.
Is CVE-2026-30939 an authenticated vulnerability?
No, CVE-2026-30939 is an unauthenticated vulnerability that can be exploited by attackers without any credentials.