CVE-2026-34573: Parse server Denial of Service Vulnerability
HIGHCVE-2026-34573 is a HIGH denial of service vulnerability (CWE-407: Inefficient Algorithmic Complexity) affecting Parse server libraries in the npm ecosystem. The issue involves parse-server has graphql complexity validator exponential fragment traversal dos. Remediation is available by upgrading affected packages to version 9.7.0-alpha.12, 8.6.68.
CVE-2026-34573 at a Glance
How to Fix CVE-2026-34573
To remediate this vulnerability, upgrade all affected Parse server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install parse-server@9.7.0-alpha.12npm install parse-server@8.6.68Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls parse-serverHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-34573, inspect your project dependencies using npm:
npm ls parse-serverAnalyze the terminal output to locate any version of Parse server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.7.0-alpha.12), your application is affected.
Note: The npm ls parse-server command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-407: Inefficient Algorithmic Complexity, where an algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached. In Parse server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-34573 Affected Parse server Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
parse-server
|
npm |
≥ 9.0.0
< 9.7.0-alpha.12
|
9.7.0-alpha.12
|
|
parse-server
|
npm |
< 8.6.68
|
8.6.68
|
References
Frequently Asked Questions
What is CVE-2026-34573?
Which Parse server versions are affected?
What version fixes CVE-2026-34573?
Is parse-server affected?
What CWE is associated with CVE-2026-34573?
How can I check npm dependencies for CVE-2026-34573?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-mfj6-6p54-m98c",
"modified" : "2026-03-31T23:49:18Z",
"published" : "2026-03-31T23:49:18Z",
"aliases" : [ "CVE-2026-34573" ],
"summary" : "parse-server has GraphQL complexity validator exponential fragment traversal DoS",
"details" : "### Impact\n\nThe 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.\n\n### Patches\n\nThe 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.\n\n### Workarounds\n\nDisable GraphQL complexity limits by setting `requestComplexity.graphQLDepth` and `requestComplexity.graphQLFields` to `-1` (the default).\n\n### Resources\n\n- GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-mfj6-6p54-m98c\n- Fix Parse Server 9: https://github.com/parse-community/parse-server/pull/10344\n- Fix Parse Server 8: https://github.com/parse-community/parse-server/pull/10345",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "parse-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "9.0.0"
}, {
"fixed" : "9.7.0-alpha.12"
} ]
} ]
}, {
"package" : {
"ecosystem" : "npm",
"name" : "parse-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "8.6.68"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/parse-community/parse-server/security/advisories/GHSA-mfj6-6p54-m98c"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34573"
}, {
"type" : "WEB",
"url" : "https://github.com/parse-community/parse-server/pull/10344"
}, {
"type" : "WEB",
"url" : "https://github.com/parse-community/parse-server/pull/10345"
}, {
"type" : "WEB",
"url" : "https://github.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295"
}, {
"type" : "WEB",
"url" : "https://github.com/parse-community/parse-server/commit/f759bda075298ec44e2b4fb57659a0c56620483b"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/parse-community/parse-server"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-407" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-03-31T23:49:18Z",
"nvd_published_at" : "2026-03-31T16:16:33Z"
}
}