MongoDBDatabase / datastore
CVE-2026-1849
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 · uneditedMongoDB Server may experience an out-of-memory failure while evaluating expressions that produce deeply nested documents. The issue arises in recursive functions because the server does not periodically check the depth of the expression.
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 · moderate confidenceMongoDB Server contains a vulnerability in its expression evaluation engine where recursive functions processing deeply nested documents fail to periodically check recursion depth. This allows attackers to trigger out-of-memory conditions by submitting queries that produce or reference deeply nested documents, causing the server to exhaust available memory.
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
>= 7.0.0, < 7.0.29>= 8.0.0, < 8.0.18>= 8.2.0, < 8.2.2CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Determine installed MongoDB versionRun 'db.version()' in the mongo shell or 'mongod --version' from command lineAffected if The version falls within >= 7.0.0, < 7.0.29; >= 8.0.0, < 8.0.18; or >= 8.2.0, < 8.2.2
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Identify exposure to untrusted query inputReview application architecture to determine if external or untrusted users can submit queries to the MongoDB serverAffected if External users or untrusted applications can submit arbitrary queries to the affected MongoDB instance
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Check for deep document nesting in existing dataUse db.collection.find().limit(100) to inspect document structures, or query for documents with high depth using aggregation pipelines that traverse nested fieldsAffected if The database contains documents with deeply nested structures (typically dozens of nesting levels) that could be processed by vulnerable query expressions
You are affected if your MongoDB version is within the affected ranges AND untrusted users can submit queries that process deeply nested documents in your database.
Generated from the published advisory. Verify against your own configuration.
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.
dbcve · scoped7.0.298.0.188.2.2
Apply vendor-provided patches when available. In the interim, consider limiting document nesting depth in applications and implementing query complexity limits at the application or proxy layer to reduce attack surface.
Upgrade to MongoDB 7.0.29+ (for 7.x users), 8.0.18+ (for 8.0.x users), or 8.2.2+ (for 8.2.x users)
- 1. Determine current MongoDB version using: db.version() or mongod --version
- 2. Based on your current version, identify the target fixed release: if 7.0.x upgrade to 7.0.29+, if 8.0.x upgrade to 8.0.18+, if 8.2.0-8.2.1 upgrade to 8.2.2+
- 3. Back up all MongoDB data before upgrading
- 4. Test the upgrade in a non-production environment first
- 5. For standalone instances: stop MongoDB, install new version, start MongoDB
- 6. For replica sets: perform rolling upgrade (upgrade secondary nodes first, then primary)
- 7. Verify upgrade successful by checking: db.version() returns fixed version
- 8. Monitor server logs for any out-of-memory errors related to nested documents
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in MongoDB
Scoped from the published advisory
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-1849 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-1849 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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