CVE-2026-30939: Parse Server Denial of Service and Cloud Function Dispatch Bypass Vulnerability
Summary
CVE-2026-30939: 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. Affects parse-server across 2 version ranges.
< 8.6.13
>= 9.0.0-alpha.1, < 9.5.1-alpha.2
Fixed in 8.6.13 or 9.5.1-alpha.2, depending on the release line you run. How to fix ↓
Also tracked for
- parse · Bitnami
The same CVE-2026-30939 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Parse Server is an open-source backend framework that enables developers to build applications with a robust server-side infrastructure. It provides features such as data storage, user authentication, and cloud functions, which allow developers to execute custom server-side logic. However, due to its design, Parse Server is vulnerable to certain attacks that exploit its handling of prototype properties, leading to potential denial of service and unauthorized access to cloud functions.
Vulnerability Detail
The vulnerability arises from the way Parse Server processes Cloud Function requests. An unauthenticated attacker can exploit this by invoking a Cloud Function endpoint using a prototype property name as the function name. This results in infinite recursion, causing a call stack size error that crashes the server process. Additionally, other prototype property names can bypass the Cloud Function dispatch validation, returning HTTP 200 responses even when no corresponding Cloud Functions are defined. This vulnerability affects all Parse Server deployments that expose the Cloud Function endpoint.
How To Fix
Latest published version: 9.10.5 as of 22 Oct 2026
npm install parse-server@9.10.5Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 8.6.138.6.13npm install parse-server@8.6.13 -
>= 9.0.0-alpha.1, < 9.5.1-alpha.29.5.1-alpha.2npm install parse-server@9.5.1-alpha.2
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Workaround
As a temporary measure, place a reverse proxy or Web Application Firewall (WAF) in front of your Parse Server instance to block requests that attempt to access Object.prototype property names. This can help mitigate the risk until a proper patch is applied.
Conclusion
CVE-2026-30939 presents a significant risk to Parse Server deployments by allowing denial of service attacks and unauthorized access to cloud functions. It is crucial for developers to update their Parse Server installations to the latest patched versions and implement recommended workarounds to mitigate the risk.
See every vulnerability recorded for parse-server →
FAQ
CVE-2026-30939 is a vulnerability in Parse Server that allows unauthenticated attackers to crash the server or bypass Cloud Function dispatch validation.
If your application uses Parse Server and exposes Cloud Function endpoints, it is at risk of denial of service attacks and unauthorized access to functions.
All versions of Parse Server that expose Cloud Function endpoints are affected, particularly versions prior to 8.6.13 and 9.5.1-alpha.2.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Visit Vulert Scanner to check your application without signup.
The CVSS score for this vulnerability is 8.8, indicating a high severity level.
References
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