CVE-2026-96299

Missing Authorization Check on Internal Aggregation Stage in MongoDB Server mongos Leads to Denial of Service

Published Oct 13, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
A security issue was discovered in MongoDB mongos (the sharded cluster router) where an authenticated user with readWrite privileges could crash the mongos process by crafting a specially formed aggregation pipeline. The issue leverages an internal aggregation stage that lacks proper authorization checks despite being intended for internal use, allowing a subsequent stage to be forced to execute on the router under conditions it was not designed to handle. This results in an unhandled fatal error that causes the mongos process to immediately abort, resulting in denial of service for all clients routed through the affected mongos instance.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Weaknesses CWE-770
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Mongodb
Mongodb mongodb Server
Vendors & Products Mongodb
Mongodb mongodb Server
Type Values Removed Values Added
Description Missing limits on resource use in the match expression evaluator of MongoDB Server can cause the server to consume excessive memory. Internal schema validation operators that are meant only for server use are accepted in user-supplied query filters. When these operators are nested and applied to documents that contain arrays, the server evaluates every combination of array elements without a sufficient limit on the resources used. This can cause memory use to grow until the mongod process runs out of memory and terminates. The behavior can occur when an authenticated user with read-only privileges runs an aggregation query that nests these operators. A security issue was discovered in MongoDB mongos (the sharded cluster router) where an authenticated user with readWrite privileges could crash the mongos process by crafting a specially formed aggregation pipeline. The issue leverages an internal aggregation stage that lacks proper authorization checks despite being intended for internal use, allowing a subsequent stage to be forced to execute on the router under conditions it was not designed to handle. This results in an unhandled fatal error that causes the mongos process to immediately abort, resulting in denial of service for all clients routed through the affected mongos instance.
Title MongoDB Nested `$_internalSchemaAllElemMatchFromIndex` Cross-Product MatchExpression OOM Missing Authorization Check on Internal Aggregation Stage in MongoDB Server mongos Leads to Denial of Service
Weaknesses CWE-617
Type Values Removed Values Added
Description Missing limits on resource use in the match expression evaluator of MongoDB Server can cause the server to consume excessive memory. Internal schema validation operators that are meant only for server use are accepted in user-supplied query filters. When these operators are nested and applied to documents that contain arrays, the server evaluates every combination of array elements without a sufficient limit on the resources used. This can cause memory use to grow until the mongod process runs out of memory and terminates. The behavior can occur when an authenticated user with read-only privileges runs an aggregation query that nests these operators.
Title MongoDB Nested `$_internalSchemaAllElemMatchFromIndex` Cross-Product MatchExpression OOM
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mongodb
Published
Updated
Oct 13, 2026, 4:31 PM
Reserved
Sep 22, 2026, 10:29 PM
Status
Awaiting Analysis
Published
Oct 13, 2026, 4:17 PM
Modified
Oct 15, 2026, 8:38 PM