CVE-2026-34573: Parse Community Parse Server DoS in GraphQL complexity validator

CVE-2026-34573 · Severity: high · CVSS 7.5 · Published 2026-03-31

Parse Server is an open-source backend framework used to build and host applications. A vulnerability in its GraphQL component allows an attacker to crash or freeze the service by sending a specially crafted request. This can lead to a total service outage for all users, even if the attacker is not logged in.

Technologies: parse-server (npm). Vendors: npm.

Quick answers

Is CVE-2026-34573 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-34573 being exploited in the wild.
How severe is CVE-2026-34573?
High severity, with a CVSS score of 7.5, published 31 March 2026.
Which products and versions are affected?
parse-server (npm) SEMVER:introduced=9.0.0,fixed=9.7.0-alpha.12.
Is there a fix for CVE-2026-34573?
Yes. parse-server (npm): upgrade to 9.7.0-alpha.12 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-34573 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-34573?
Check whether you run parse-server (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • parse-server (npm): upgrade to 9.7.0-alpha.12 or later
    npm install parse-server@9.7.0-alpha.12

Technical details

An algorithmic complexity vulnerability (CWE-407) exists in the GraphQL query complexity validator of Parse Server. The root cause is an exponential O(2^N) fragment traversal during the validation of GraphQL queries containing binary fan-out fragment spreads. An unauthenticated remote attacker can exploit this by sending a crafted GraphQL query, which blocks the Node.js event loop for several seconds, leading to a denial-of-service (DoS). This issue specifically affects deployments where 'requestComplexity.graphQLDepth' or 'requestComplexity.graphQLFields' are enabled. The vulnerability is patched in versions 8.6.68 and 9.7.0-alpha.12 by implementing memoized fragment computation and early termination.

Affected products

  • Parse Community Parse Server < 8.6.68, >= 9.0.0 < 9.7.0-alpha.12

Identifiers

  • CVE-2026-34573
  • GHSA-mfj6-6p54-m98c

Timeline

  • 2026-03-29: advisory: Vendor advisory GHSA-mfj6-6p54-m98c published
  • 2026-03-31: disclosed: CVE-2026-34573 published to NVD

References

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