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NVD / CVE Program· CNA mongodb

CVE-2026-18691: Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure

CriticalCVSS 9.0 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 36/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.35% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: MongoDB MongoDB Server 7.0.40, 8.0.29, 8.3.8.

Low priority for now. Upgrade to MongoDB MongoDB Server 7.0.40, 8.0.29, 8.3.8 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An issue in MongoDB Server's intra-cluster connection setup could allow a party with suitable network access to influence which authentication mechanism is used when one replica set member connects to another. Under certain conditions, this could cause the cluster's shared internal credential to be transmitted in a less-protected form, potentially allowing that credential to be recovered. If recovered, the credential could be used to authenticate as the internal superuser to nodes in the deployment.

Published
Aug 11, 2026
Updated
Oct 23, 2026
EPSS
0.3% · 29th percentile

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JSON

Action score

36

Monitor

Low priority for now.

CVSS
36 / 40 · 9.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · mongodb
9.0
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-18691

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mongodbmongodb

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (mongodb). Independent of NVD's CPE analysis and usually ahead of it.

  • MongoDB MongoDB Server

    • 8.3.0 and later · before 8.3.8affected · semver
    • 8.0 and later · before 8.0.29affected · semver
    • 7.0 and later · before 7.0.40affected · semver
Affected versions · NVD (6)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mongodb mongodb7.0.0 and later · before 7.0.40
  • mongodb mongodb8.0.0 and later · before 8.0.29
  • mongodb mongodb8.2.0 and later · up to 8.2.12 inclusive
  • mongodb mongodb8.3.0 and later · before 8.3.8
  • mongodb mongodb9.0.0
  • mongodb mongodb9.1.0

Same product

mongodb: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-14847Zlib compressed protocol header length confusion may allow memory readKEV
    89Now
  • CVE-2013-1892MongoDB before 2.0.9 and 2.2.x before 2.2.4 does not properly validate requests to the nativeHelper function in SpiderMonkey, which allows…
    40Plan
  • CVE-2025-3085MongoDB Server running on Linux may allow unexpected connections where intermediate certificates are revoked
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-18688Aug 11, 2026 · Out-of-Bounds Read in MongoDB Aggregation Framework Leads to Denial of Service and Potential Memory Disclosure
    28Monitor
  • ← EarlierCVE-2026-18690Aug 11, 2026 · Improper Authorization in MongoDB Server Allows Unauthorized Actions on System Collections
    28Monitor
  • Later →CVE-2026-18692Aug 11, 2026 · Use-After-Free in MongoDB Timeseries Bucket Handling Leads to Denial of Service and Potential Remote Code Execution
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
MongoDB MongoDB Server7.0.40Vendor (CNA)
MongoDB MongoDB Server8.0.29Vendor (CNA)
MongoDB MongoDB Server8.3.8Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-186920 days apartUse-After-Free in MongoDB Timeseries Bucket Handling Leads to Denial of Service and Potential Remote Code Execution
    30Monitor
  • CVE-2026-187060 days apartUse-After-Free in MongoDB $graphLookup Aggregation Stage Leads to Denial of Service and Potential Remote Code Execution
    30Monitor
  • CVE-2026-187080 days apartImproper Neutralization of Input in MongoDB Server's JavaScript Scripting Engine Leads to Unauthorized Code Execution Within Query Scopes
    21Monitor
  • CVE-2026-8206028 days apartInsufficient Validation of Shard Key Values in MongoDB Server Leads to Query Operator Injection in Change Stream Post-Image Lookups
    9Monitor

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Not on record for this CVE: patch commit or PR link · researcher credit.

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-757 · Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')

CVSS vector

CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records