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

Source: https://junglewise.ai/threats/cve-2026-34573-parse-community-parse-server-dos-in-graphql-complexity-validator  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-31. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/parse-server). Vendors: [npm](https://junglewise.ai/threats/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

  ```sh
  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

- [https://github.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295](https://github.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295)
- [https://github.com/parse-community/parse-server/commit/f759bda075298ec44e2b4fb57659a0c56620483b](https://github.com/parse-community/parse-server/commit/f759bda075298ec44e2b4fb57659a0c56620483b)
- [https://github.com/parse-community/parse-server/pull/10344](https://github.com/parse-community/parse-server/pull/10344)
- [https://github.com/parse-community/parse-server/pull/10345](https://github.com/parse-community/parse-server/pull/10345)
- [https://github.com/parse-community/parse-server/security/advisories/GHSA-mfj6-6p54-m98c](https://github.com/parse-community/parse-server/security/advisories/GHSA-mfj6-6p54-m98c)

## Related threats

- [Duplicate Advisory: Parse Server vulnerable to stored XSS via malformed Content-Type bypassing file upload extension blocklist](https://junglewise.ai/threats/duplicate-advisory-parse-server-vulnerable-to-stored-xss-via-malformed-00d8867c)
- [Parse Server stored XSS via malformed Content-Type bypass](https://junglewise.ai/threats/cve-2026-61448-parse-server-stored-xss-via-malformed-content-type-bypass)
- [Parse Server information disclosure in LiveQuery ACL transitions](https://junglewise.ai/threats/cve-2026-57481-parse-server-information-disclosure-in-livequery-acl-transitions)
- [Parse Community Parse Server denial of service via nested query operators](https://junglewise.ai/threats/cve-2026-57480-parse-community-parse-server-denial-of-service-via-nested-query)
- [Parse Server stored XSS via file upload extension bypass](https://junglewise.ai/threats/cve-2026-55778-parse-server-stored-xss-via-file-upload-extension-bypass)