CVE-2026-18691

Summary

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.

Affected Software

VendorProductVersion RangeStatus
MongoDBMongoDB Server8.3.0 < 8.3.8affected
MongoDBMongoDB Server8.0 < 8.0.29affected
MongoDBMongoDB Server7.0 < 7.0.40affected

Weaknesses

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

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References