{"id":"CVE-2026-47138","aliases":["BIT-parse-2026-47138","EUVD-2026-36535","GHSA-38m6-82c8-4xfm"],"status":"published","title":"Parse Server: Pre-authentication denial of service via client version header regex backtracking","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.","severity":{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00584,"percentile":0.48264,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1333"],"published":"2026-05-23T00:11:25Z","modified":"2026-10-28T02:30:24Z","fixes":[{"ecosystem":"npm","package":"parse-server","fixed_in":["9.9.1-alpha.1","8.6.77"],"sources":["ghsa","osv"]},{"ecosystem":"Bitnami","package":"parse","fixed_in":["8.6.77","9.9.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"parse-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"9.0.0"},{"fixed":"9.9.1-alpha.1"}]}]},{"source":"ghsa","ecosystem":"npm","package":"parse-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.6.77"}]}]},{"source":"osv","ecosystem":"Bitnami","package":"parse","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"8.6.77"},{"introduced":"9.0.0"},{"fixed":"9.9.1"}]}]},{"source":"osv","ecosystem":"npm","package":"parse-server","ranges":[{"type":"SEMVER","events":[{"introduced":"9.0.0"},{"fixed":"9.9.1-alpha.1"}]}]},{"source":"osv","ecosystem":"npm","package":"parse-server","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"8.6.77"}]}]}],"products":[{"vendor":"parse-community","product":"parse-server"}],"references":[{"url":"https://github.com/parse-community/parse-server/security/advisories/GHSA-38m6-82c8-4xfm","tags":["x_refsource_CONFIRM","web","advisory"]},{"url":"https://github.com/parse-community/parse-server/pull/10463","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/parse-community/parse-server/pull/10464","tags":["x_refsource_MISC","web","fix"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47138","tags":["web","advisory"]},{"url":"https://github.com/advisories/GHSA-38m6-82c8-4xfm"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47138.json","tags":["advisory"]},{"url":"https://github.com/parse-community/parse-server","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-47138","title":"Parse Server: Pre-authentication denial of service via client version header regex backtracking","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.","status":"published","published":"2026-06-12T18:22:02.751Z","modified":"2026-06-12T18:56:14.419Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T13:36:40.478484Z"}],"euvd":[{"id":"EUVD-2026-36535","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.","status":"published","published":"2026-06-12T18:22:02Z","modified":"2026-06-12T18:56:14Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:20:43.222Z"}],"ghsa":[{"id":"GHSA-38m6-82c8-4xfm","title":"Parse Server: Pre-authentication denial of service via client version header regex backtracking","description":"### Impact\n\nAn 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.\n\n### Patches\n\nThe client SDK version capture and parsing have been removed entirely. The Parse JS SDK compatibility table defines a strict version-pinned contract between Parse Server and the Parse JS SDK; server-side adaptation to client SDK version is an obsolete pattern that contradicts that contract. The vulnerable parser, the `clientSDK` parameter that threaded its output through routers, and the legacy code path it gated are all removed. The `X-Parse-Client-Version` header and `_ClientVersion` JSON body field are now silently ignored on every request; supported Parse SDKs are unaffected.\n\n### Workarounds\n\nDeploy a reverse proxy or WAF in front of Parse Server that strips or strictly size-limits the `X-Parse-Client-Version` header AND the `_ClientVersion` field in JSON request bodies on every `/parse/*` route before forwarding to the server. A header-size cap alone is insufficient: the body-field variant requires inspection of JSON content. Upgrading to the patched version is the recommended remediation.","status":"published","published":"2026-05-23T00:11:25Z","modified":"2026-06-12T21:59:41Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T14:40:27.329706Z"}],"nvd":[{"id":"CVE-2026-47138","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.","status":"published","published":"2026-06-12T19:16:28.257Z","modified":"2026-10-26T11:10:00.157Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T14:12:23.846948Z"}],"osv":[{"id":"CVE-2026-47138","title":"Parse Server: Pre-authentication denial of service via client version header regex backtracking","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.","status":"published","published":"2026-06-12T18:22:02.751Z","modified":"2026-10-28T02:30:24.883950225Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T15:45:06.231145Z"},{"id":"GHSA-38m6-82c8-4xfm","title":"Parse Server: Pre-authentication denial of service via client version header regex backtracking","description":"### Impact\n\nAn 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.\n\n### Patches\n\nThe client SDK version capture and parsing have been removed entirely. The Parse JS SDK compatibility table defines a strict version-pinned contract between Parse Server and the Parse JS SDK; server-side adaptation to client SDK version is an obsolete pattern that contradicts that contract. The vulnerable parser, the `clientSDK` parameter that threaded its output through routers, and the legacy code path it gated are all removed. The `X-Parse-Client-Version` header and `_ClientVersion` JSON body field are now silently ignored on every request; supported Parse SDKs are unaffected.\n\n### Workarounds\n\nDeploy a reverse proxy or WAF in front of Parse Server that strips or strictly size-limits the `X-Parse-Client-Version` header AND the `_ClientVersion` field in JSON request bodies on every `/parse/*` route before forwarding to the server. A header-size cap alone is insufficient: the body-field variant requires inspection of JSON content. Upgrading to the patched version is the recommended remediation.","status":"published","published":"2026-05-23T00:11:25Z","modified":"2026-06-16T13:26:25.320958741Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T15:46:35.406455Z"},{"id":"BIT-parse-2026-47138","title":"Parse Server: Pre-authentication denial of service via client version header regex backtracking","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, 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.","status":"published","published":"2026-06-16T12:40:05.15Z","modified":"2026-06-16T13:26:25.320958741Z","updated_at":"2026-11-02T15:28:34.343258Z"}]}}