{"id":"CVE-2026-34573","aliases":["BIT-parse-2026-34573","GHSA-mfj6-6p54-m98c"],"url":"https://o3.security/vulnerability/CVE-2026-34573","summary":"Parse Server: 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","published":"2026-03-31T15:06:33.372Z","modified":"2026-08-12T03:51:44.208211885Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"parse-server","fixedVersion":"9.7.0-alpha.12"},{"ecosystem":"npm","name":"parse-server","fixedVersion":"8.6.68"}],"fix":{"url":"https://github.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295","label":"parse-community/parse-server@ea15412"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34573.json"},{"type":"ADVISORY","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":"FIX","url":"https://github.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295"},{"type":"FIX","url":"https://github.com/parse-community/parse-server/commit/f759bda075298ec44e2b4fb57659a0c56620483b"},{"type":"FIX","url":"https://github.com/parse-community/parse-server/pull/10344"},{"type":"FIX","url":"https://github.com/parse-community/parse-server/pull/10345"},{"type":"PACKAGE","url":"https://github.com/parse-community/parse-server"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:44.208211885Z"}}