Parse Server: Denial of service via exponential-time processing of deeply nested query operators

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.12 and 8.6.82, deeply nested $or, $and, and $nor query condition operators in the REST API or LiveQuery query handling could trigger exponential-time processing in the internal query-traversal helper and block the Node.js event loop. This issue is fixed in versions 9.9.1-alpha.12 and 8.6.82.

Source published

8 Jul 2026 20:53:21 UTC

Source modified

9 Jul 2026 13:43:23 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 8.7 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

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.12 and 8.6.82, deeply nested $or, $and, and $nor query condition operators in the REST API or LiveQuery query handling could trigger exponential-time processing in the internal query-traversal helper and block the Node.js event loop. This issue is fixed in versions 9.9.1-alpha.12 and 8.6.82.

Source published

Jul 8, 2026, 8:53:21 PM (timezone not stated)

Source modified

Jul 9, 2026, 1:43:23 PM (timezone not stated)

Observed here

7 Nov 2026 12:38:10 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 8.7 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

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.12 and 8.6.82, deeply nested $or, $and, and $nor query condition operators in the REST API or LiveQuery query handling could trigger exponential-time processing in the internal query-traversal helper and block the Node.js event loop. This issue is fixed in versions 9.9.1-alpha.12 and 8.6.82.

Source published

8 Jul 2026 21:16:50 UTC

Source modified

25 Oct 2026 17:10:00 UTC

Observed here

27 Oct 2026 15:15:28 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.7 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

### Impact Parse Server is vulnerable to denial of service. A remote attacker can send a single, small query (~1 KB) containing deeply nested query condition operators. Parse Server processes the nested structure with exponential time complexity, which blocks the Node.js event loop and makes the server unresponsive to all clients for the duration of processing. A single request can occupy the event loop for many seconds, and the request is repeatable. The issue affects the REST API and LiveQuery query handling and is reachable in the default configuration. Exploitation requires only the public application identifier; no user authentication is needed. ### Patches The internal query-traversal helper that previously re-walked nested arrays — causing exponential-time processing of nested `$or`/`$and`/`$nor` operators — was corrected to traverse queries in linear time. Additionally, the optional `requestComplexity.queryDepth` limit was generalized so that nested logical operators are counted even when wrapped inside field-level operators (e.g. `$elemMatch`, `$not`) or plain field names, closing a bypass of the limit on both the REST API and LiveQuery. ### Workarounds There is no complete configuration-only workaround on affected versions. Setting `requestComplexity.queryDepth` to a small positive integer reduces exposure but does not fully prevent the issue, because the limit can be bypassed by nesting the operators inside a field-level operator. Upgrading is strongly recommended.

Source published

19 Jun 2026 14:50:14 UTC

Source modified

14 Jul 2026 16:40:34 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · 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

Publisher rating · HIGH