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MongoDBDatabase / datastore

CVE-2018-20802

MEDIUM · 6.5 CVSS v3.1 Published 2020-11-23
Fix available
A fix is available. Upgrade to 3.6.9 / 4.0.3 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries with compound indexes affecting QueryPlanner. This issue affects MongoDB Server v3.6 versions prior to 3.6.9 and MongoDB Server v4.0 versions prior to 4.0.3.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

MongoDB Server contains a denial-of-service vulnerability in the QueryPlanner component where a database user with query permissions can trigger a crash by issuing specially crafted queries involving compound indexes.

MitigationUpgrade MongoDB Server to version 3.6.9 or later (for v3.6 branches) or version 4.0.3 or later (for v4.0 branches).

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
MongoDBDatabase / datastore
Affected:>= 3.6.0, < 3.6.9>= 4.0.0, < 4.0.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed MongoDB version
    Run 'db.version()' in the mongo shell or use 'mongod --version' from command line
    Affected if Version is >= 3.6.0 and < 3.6.9, or >= 4.0.0 and < 4.0.3
  2. Identify compound indexes in databases
    Run 'db.getCollectionNames().forEach(function(c) { db[c].getIndexes().forEach(function(i) { if (Object.keys(i.key).length > 1) print(c + ': ' + JSON.stringify(i.key)); }); });' in each database
    Affected if Any compound index (index with more than one field) exists in the database
  3. Verify user query permissions exist
    Run 'db.system.users.find({roles: {$elemMatch: {role: {$in: ['read', 'readWrite', 'readAnyDatabase', 'readWriteAnyDatabase']}}})' to list users with query permissions
    Affected if Any authenticated user has query or higher permissions (typical for most deployments)

Environment is affected if MongoDB version is in the vulnerable range and compound indexes exist, since an authenticated user with query permissions can trigger the crash via specially crafted queries on those indexes.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 3.6.9 / 4.0.3 or later
Fixed in 3.6.94.0.3
Interim mitigation

Upgrade MongoDB Server to version 3.6.9 or later (for v3.6 branches) or version 4.0.3 or later (for v4.0 branches).

Fix this in MongoDB Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,950
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-20802 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data