Summary
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
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.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
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.
Frequently Asked Questions
- What is CVE-2026-34573? CVE-2026-34573 is a high-severity security vulnerability in parse-server (npm), affecting versions >= 9.0.0, < 9.7.0-alpha.12. It is fixed in 9.7.0-alpha.12, 8.6.68.
- Which versions of parse-server are affected by CVE-2026-34573? parse-server (npm) versions >= 9.0.0, < 9.7.0-alpha.12 is affected.
- Is there a fix for CVE-2026-34573? Yes. CVE-2026-34573 is fixed in 9.7.0-alpha.12, 8.6.68. Upgrade to this version or later.
- Is CVE-2026-34573 exploitable, and should I be worried? Whether CVE-2026-34573 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-34573 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-34573?
- Upgrade
parse-serverto 9.7.0-alpha.12 or later - Upgrade
parse-serverto 8.6.68 or later
- Upgrade