# CVE-2026-18691

## Summary

- **CVE ID:** CVE-2026-18691
- **Severity:** CRITICAL
- **CVSS Score:** 9 (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)
- **CWE:** CWE-757
- **Published:** Aug 11, 2026
- **Last Modified:** Aug 11, 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.

## Affected Products

- MongoDB — MongoDB Server (8.3.0)
- MongoDB — MongoDB Server (8.0)
- MongoDB — MongoDB Server (7.0)

## References

- [CNA](https://jira.mongodb.org/browse/SERVER-130264)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.24%
- **EPSS Percentile:** 14.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._