CVE-2026-18691
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk14th percentile - higher than 14% of all known CVEs
Summary
A vulnerability in MongoDB Server's intra-cluster connection setup allows a party with suitable network access to influence the authentication mechanism used between replica set members. Under certain conditions, this could cause the cluster's shared internal credential to be transmitted in a less-protected form, potentially allowing its recovery. If recovered, the credential could be used to authenticate as the internal superuser.
Risk Assessment
The risk includes potential credential theft, which could lead to unauthorized access to cluster nodes with superuser privileges.
Recommendation
Update MongoDB Server to a patched version and secure the network to limit access to replica set communication.
Original NVD description (English source)
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.