How severe is CVE-2026-34573?

No CVSS score has been assigned to CVE-2026-34573 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-34573?

CVE-2026-34573 affects the following packages: parse-server (npm), parse-server (npm). Ecosystems affected: npm.

How do I fix CVE-2026-34573?

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.

How do I detect CVE-2026-34573 in my npm dependencies?

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.

How do I mitigate CVE-2026-34573 if there is no patch (or I can't update yet)?

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.

Is CVE-2026-34573 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-34573 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-34573?

CVE-2026-34573 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 51th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-34573?

CVE-2026-34573 is classified as CWE-407 (CWE-407). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-34573 published, and has it been updated?

CVE-2026-34573 was published on March 31, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-34573 — parse-server

Fix: parse-community/parse-server@ea15412

CVE-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

Also known asBIT-parse-2026-34573GHSA-mfj6-6p54-m98c

Published

Mar 31, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs51th percentile — riskier than 51% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

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.

62other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

parse-servernpm

50Kdownloads / week

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

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`parse-server`	≥ 9.0.0&&< 9.7.0-alpha.12	9.7.0-alpha.12`npm install parse-server@9.7.0-alpha.12`
📦npm	`parse-server`	all versions	8.6.68`npm install parse-server@8.6.68`

Affected Products

1 product · 13 configurations

Application

parse-serverparseplatform

≥ 9.0.0 && < 9.7.0

1 version

9.7.0

Detection & mitigation playbook

Open-source dependency

Detect
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.

Frequently Asked Questions

### 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. Addi

O3 Security · Impact-Aware SCA

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