Parse Server has Denial of Service (DoS) and Cloud Function Dispatch Bypass via Prototype Chain Resolution

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-30939: 0.51% estimated exploitation activity in the next 30 days; percentile 43.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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:…

Published by the source

10 Mar 2026, 00:57 UTC

Last modified by the source

16 Mar 2026, 03:09 UTC

Source last checked

26 Oct 2026, 12:43 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5j86-7r7m-p8h6

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-5j86-7r7m-p8h6

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# Patch Next advisory brief: CVE-2026-30939

Advisory: Parse Server has Denial of Service (DoS) and Cloud Function Dispatch Bypass via Prototype Chain Resolution
IDs: CVE-2026-30939, GHSA-5j86-7r7m-p8h6
Record: https://patchnext.com/advisories/cve-2026-30939 (revision 3, source checked 26 Oct 2026, 12:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: parse-server 9.5.1-alpha.2, 8.6.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm parse-server: affected < 8.6.13; >= 9.0.0-alpha.1, < 9.5.1-alpha.2; fixed in 8.6.13, 9.5.1-alpha.2

## Suggested inspection (read-only)
- `npm ls parse-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on parse-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-5j86-7r7m-p8h6 (OSV record GHSA-5j86-7r7m-p8h6 lists affected ranges: npm parse-server >=0 =9.0.0-alpha.1 <9.5.1-alpha.2 (fixed))
- Verified: https://github.com/advisories/GHSA-5j86-7r7m-p8h6 (GitHub-reviewed advisory GHSA-5j86-7r7m-p8h6 lists affected ranges: npm parse-server >=0 =9.0.0-alpha.1 <9.5.1-alpha.2)

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