What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-24 · updated 2026-10-24
• Weakness: CWE-209

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.

Affected products

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

How to fix

Upgrade to a fixed version: parse-community parse-server 8.6.86, 9.10.0-alpha.5. Check the vendor advisory for mitigations.

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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