CVE-2026-34573

Description

### Impact 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. ### Patches The fix replaces the per-branch fragment traversal with memoized fragment computation, reducing the traversal from exponential O(2^N) to linear O(N) time. Additionally, early termination aborts the traversal as soon as configured limits are exceeded. ### Workarounds Disable GraphQL complexity limits by setting `requestComplexity.graphQLDepth` and `requestComplexity.graphQLFields` to `-1` (the default). ### Resources - GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-mfj6-6p54-m98c - Fix Parse Server 9: https://github.com/parse-community/parse-server/pull/10344 - Fix Parse Server 8: https://github.com/parse-community/parse-server/pull/10345

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 0.0%, 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