Auth bypass in MongoDB
CVE-2026-18703
An issue in MongoDB Server could allow a party with a valid client certificate and a corresponding user account to authenticate using a certificate-based authentication method, even when an administrator has configured the server to restrict authentication to other mechanisms. This could allow authentication through a method the administrator intended to disable.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.001 (3.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 3rd percentile — 3.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: +0.000
Affected products
- MongoDB — versions 9.0.0, 9.1.0
- MongoDB Server — versions 8.3.0
Weakness classification (CWE)
References
- jira.mongodb.org/browse/SERVER-127863 (Issue Tracking, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-18703?
- CVE-2026-18703 is a medium-severity vulnerability in MongoDB, classified under Incorrect Authorization. CVSS score: 4.2/10. Published 2026-08-11.
- How severe is CVE-2026-18703?
- Medium severity. CVSS v3 base score is 4.2 out of 10.