CVE-2026-34573 — parse-server
Fix: parse-community/parse-server@ea15412CVE-2026-34573 is a CWE-407 vulnerability in parse-server. A fix is available for parse-server — see the affected versions and patch details below.
Parse Server: GraphQL complexity validator exponential fragment traversal DoS
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34573.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
parse-servernpmDescription
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | parse-server | ≥ 9.0.0&&< 9.7.0-alpha.12 | 9.7.0-alpha.12npm install parse-server@9.7.0-alpha.12 |
| 📦npm | parse-server | all versions | 8.6.68npm install parse-server@8.6.68 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for parse-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update parse-server to 9.7.0-alpha.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34573 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34573 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34573. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-34573 in your dependencies?
O3 Security finds CVE-2026-34573 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.