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Description

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.

PUBLISHED Reserved 2026-05-18 | Published 2026-06-12 | Updated 2026-06-12 | Assigner GitHub_M




HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-1333: Inefficient Regular Expression Complexity

Product status

< 8.6.77
affected

>= 9.0.0, < 9.9.1-alpha.1
affected

References

github.com/...server/security/advisories/GHSA-38m6-82c8-4xfm

github.com/parse-community/parse-server/pull/10463

github.com/parse-community/parse-server/pull/10464

cve.org (CVE-2026-47138)

nvd.nist.gov (CVE-2026-47138)

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