CVE-2026-47138

CVE-2026-47138 · Parse Server: Pre-authentication denial of service via client version header regex backtracking

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.77 and 9.9.1-alpha.1, an unauthenticated attacker who knows a publicly-known Parse Application ID can submit a single HTTP request whose client SDK version field contains adversarial input that triggers polynomial backtracking in a request-header parser. The parsing runs before session authentication and before rate limiting on every /parse/* request, so the request consumes seconds to minutes of synchronous CPU on a Node.js worker before any access control evaluates it. A small number of concurrent requests can saturate a worker; a single large request via the body-field variant can pin a worker for minutes. Production deployments running the default configuration are affected. This issue has been patched in versions 8.6.77 and 9.9.1-alpha.1.

CVSS 8.7 · High · EPSS 0.9% · Fix available

Published

2026-06-12T18:22:02.751Z

Updated

2026-06-12T18:56:14.419Z

Stack: node

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