CVE-2026-18691
Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
- State
- Published
- Severity
- 9.0 Critical
- Published
- Aug 11, 2026
- Updated
- Aug 11, 2026
- Reserved
- Aug 3, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.0 Critical | 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 | mongodb |
| 3.1 | 8.8 High | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | mongodb |
Weaknesses
- CWE-757 Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
Affected Products
| Product | Versions |
|---|---|
MongoDB ServerMongoDB |
|
References
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