What’s Vulnerable › Vulnerabilities
CVE-2026-18691: Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
- Severity: high (CVSS 8.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-08-11 · updated 2026-10-23
- Weakness: CWE-757
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.
Affected products
- MongoDB: from 7.0.0 before 7.0.40; from 8.0.0 before 8.0.29; from 8.2.0 through 8.2.12; from 8.3.0 before 8.3.8; 9.0.0-alpha0, 9.0.0-alpha1, 9.1.0-alpha0 — fixed in 7.0.40, 8.0.29, 8.3.8
How to fix
Upgrade to a fixed version: MongoDB 7.0.40, 8.0.29, 8.3.8. Check the vendor advisory for mitigations.
References
Get alerted when CVE-2026-18691 or the next vulnerability affects your stack