dbcve.org
MongoDBDatabase / datastore

CVE-2026-9740

HIGH · 7.5 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 7.0.35 / 8.0.24 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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 vulnerability in MongoDB Server's BSON validation logic allows an unauthenticated user to crash the mongod process by sending a specially crafted message. The BSON validator's handling of certain nested binary data structures permits uncontrolled mutual recursion between validation functions, where each re-entry resets internal depth tracking.

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 confidence

MongoDB Server's BSON validation logic contains a vulnerability where nested binary data structures trigger uncontrolled mutual recursion between validation functions. Each recursive re-entry resets internal depth tracking instead of properly accumulating it, leading to stack exhaustion when processing specially crafted BSON messages. An unauthenticated remote attacker can exploit this to crash the mongod process.

MitigationApply the vendor patch or upgrade to a fixed MongoDB version; in the interim, restrict network access to mongod ports and enable authentication as defense-in-depth measures.

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:>= 7.0.0, < 7.0.35>= 8.0.0, < 8.0.24>= 8.2.0, < 8.2.10>= 8.3.0, < 8.3.3

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
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 checks

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

  1. Identify installed MongoDB Server version
    Run 'db.version()' in mongosh/mongo shell, or execute 'mongod --version' from command line
    Affected if The version falls within any of these ranges: 7.0.0-7.0.34, 8.0.0-8.0.23, 8.2.0-8.2.9, or 8.3.0-8.3.2
  2. Confirm BSON validation is active
    BSON validation is enabled by default for any collection with validator rules. Check for validators via 'db.getCollectionInfos()' or review collection validation configurations
    Affected if Any collection has BSON validation rules defined, or default BSON structural validation is being performed on incoming documents
  3. Determine network exposure of mongod process
    Review mongod bind_ip configuration in config file or command line, and check firewall rules. Run 'db.serverStatus().security' or inspect net.bindIp settings
    Affected if mongod is bound to 0.0.0.0 or an IP accessible to untrusted networks, allowing unauthenticated remote attackers to send specially crafted messages

You are affected if your mongod runs an affected version AND is network-accessible to unauthenticated attackers, regardless of BSON validator configuration since the flaw exists in core BSON validation logic.

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.

dbcve · scoped
Upgrade available Upgrade to 7.0.35 / 8.0.24 / 8.2.10 or later
Fixed in 7.0.358.0.248.2.10
Interim mitigation

Apply the vendor patch or upgrade to a fixed MongoDB version; in the interim, restrict network access to mongod ports and enable authentication as defense-in-depth measures.

Recommended fix High confidence

Upgrade to 7.0.35+ (if on 7.0), 8.0.24+ (if on 8.0), 8.2.10+ (if on 8.2), or 8.3.3+ (if on 8.3); prefer the latest stable release in your branch

  1. 1. Check current MongoDB version by running: db.version() in mongosh or mongo shell
  2. 2. Based on your current version, determine the target fixed release: for 7.0.x go to 7.0.35+, for 8.0.x go to 8.0.24+, for 8.2.x go to 8.2.10+, for 8.3.x go to 8.3.3+
  3. 3. Before upgrading, perform a full backup of your data directory (default: /data/db)
  4. 4. Stop the mongod process gracefully: db.adminCommand({shutdown: 1}) or systemctl stop mongod
  5. 5. If using a package manager (apt/yum), update MongoDB: sudo apt-get update && sudo apt-get install -y mongodb-org (or corresponding yum command)
  6. 6. If upgrading manually, download the appropriate MongoDB binary from https://www.mongodb.com/try/download/community
  7. 7. Start mongod and verify successful startup in logs
  8. 8. Confirm the new version: db.version() should show a non-vulnerable version
Caveat Review MongoDB release notes for breaking changes between your current version and target version before upgrading; major version upgrades may require additional migration steps

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in MongoDB Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2026-9740 in production — separate from our analysis above.

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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