Description
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: 2026-08-11
Score: 9 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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History

Tue, 11 Aug 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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

Tue, 11 Aug 2026 19:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
Weaknesses CWE-757
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9, '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'}

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: mongodb

Published:

Updated: 2026-08-11T20:22:00.933Z

Reserved: 2026-08-03T15:53:04.081Z

Link: CVE-2026-18691

cve-icon Vulnrichment

Updated: 2026-08-11T20:21:56.137Z

cve-icon NVD

Status : Received

Published: 2026-08-11T19:17:22.903

Modified: 2026-08-11T21:17:31.620

Link: CVE-2026-18691

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-757

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