CVE-2026-34573

Description

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.68 and 9.7.0, the GraphQL query complexity validator can be exploited to cause a denial-of-service by sending a crafted query with binary fan-out fragment spreads. A single unauthenticated request can block the Node.js event loop for seconds, denying service to all concurrent users. This only affects deployments that have enabled the requestComplexity.graphQLDepth or requestComplexity.graphQLFields configuration options. This issue has been patched in versions 8.6.68 and 9.7.0.

How to fix CVE-2026-34573

To remediate CVE-2026-34573, upgrade the affected package to a fixed version below.

• —upgrade to 8.6.68 or later
• —upgrade to 9.7.0-alpha.12 or later

Is CVE-2026-34573 being exploited?

Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 8.6.68, >= 9.0.0, < 9.7.0
• >= 9.0.0, < 9.7.0-alpha.12

CVSS scores

References (7)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-34573
• PATCHgithub.com/parse-community/parse-server
• WEBgithub.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295
• WEBgithub.com/parse-community/parse-server/commit/f759bda075298ec44e2b4fb57659a0c56620483b