---
id: "CVE-2026-119569"
kind: "vulnerability"
aliases: ["CVE-2026-119569"]
title: "Parse Server: prototype pollution from user keys breaks requests until restart"
severity: "medium"
cvss: 6.0
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["backend", "node", "package", "parse-server", "self-hosted"]
not_affected_if: ["already-patched", "no-untrusted-class-write"]
published_at: "2026-10-30T14:16:45+00:00"
first_seen_at: "2026-10-30T14:30:53+00:00"
updated_at: "2026-10-30T14:32:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119569", "first_seen_at": "2026-10-30T14:30:53+00:00"}]
---

# Parse Server: prototype pollution from user keys breaks requests until restart

Parse Server expands user-supplied field keys and ACL entry names into objects without own-property checks, so crafted keys can overwrite built-in object members. A client with class write access can corrupt built-in functions, causing all requests to fail until the server restarts.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Parse Server version with `npm ls parse-server` or the version in `package.json`.
- Confirm whether any client has class write access, since the sources say that is required.

## Fix

- Move Parse Server 8.x to `8.6.108` or later.
- Move Parse Server 9.x to `9.10.5-alpha.9` or later.

## Timeline

- 2026-10-30T14:30:53+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119569

## From the sources

Parse Server before 8.6.108 and 9.0.0 before 9.10.5-alpha.9 contains a prototype pollution vulnerability because user-controlled keys are expanded into objects without own-property checks. Clients with class write access can send dot notation field keys or ACL entry names matching built-in object members to corrupt built-in functions, causing all requests to fail until server restart.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_