Vulnerability in MongoDB
CVE-2026-18691
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (26.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 26.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.001
Affected products
- MongoDB — versions 9.0.0, 9.1.0
- MongoDB Server — versions 8.3.0, 8.0, 7.0
Weakness classification (CWE)
References
- jira.mongodb.org/browse/SERVER-130264 (Issue Tracking, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-18691?
- CVE-2026-18691 is a high-severity vulnerability in MongoDB, classified under CWE-757. CVSS score: 8.8/10. Published 2026-08-11.
- How severe is CVE-2026-18691?
- High severity. CVSS v3 base score is 8.8 out of 10.