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High CVSS 8.8

CVE-2026-18691

NVD analysis in progress

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.

What this means

Exposure
Exploitable from the adjacent network, without authentication and with no action from the victim.
Impact
An attacker can read sensitive data, modify or destroy data and take the service offline.
Likelihood
Its EPSS score stays low: nothing points to imminent exploitation, which is no reason to leave it unpatched.

What to doFold into the next patch cycle.

Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.

Published
11 August 2026
CVSS
8.8 (v3.1) CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
0.24% probability of exploitation within 30 days · above 15% of all CVEs
Weakness
CWE-757
Sources
nvd
References

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