CVE-2026-120807

Privilege escalation via fail-open user lookup in X.509 cluster-membership guard

Published Nov 10, 2026 CVSS 4.0 · 7.5 High EPSS < 1% KEV · Not listed
Description
A flaw in MongoDB’s X.509 cluster-membership authentication guard could allow a holder of a cluster-member certificate to gain elevated internal privileges when a specific deployment configuration is in use. An internal check, which prevents a certificate recognized as a cluster member from also being treated as a regular user, does not correctly distinguish between certain error conditions encountered during user lookup. Under certain timing conditions, this can cause the check to be bypassed, granting the connection full internal system privileges. Triggering this issue requires possession of a valid cluster-member TLS certificate, non-default X.509 cluster authentication configuration, and specific conditions during the user cache lookup process.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Mongodb
Mongodb mongodb Server
Vendors & Products Mongodb
Mongodb mongodb Server
Type Values Removed Values Added
Description A flaw in MongoDB’s X.509 cluster-membership authentication guard could allow a holder of a cluster-member certificate to gain elevated internal privileges when a specific deployment configuration is in use. An internal check, which prevents a certificate recognized as a cluster member from also being treated as a regular user, does not correctly distinguish between certain error conditions encountered during user lookup. Under certain timing conditions, this can cause the check to be bypassed, granting the connection full internal system privileges. Triggering this issue requires possession of a valid cluster-member TLS certificate, non-default X.509 cluster authentication configuration, and specific conditions during the user cache lookup process.
Title Privilege escalation via fail-open user lookup in X.509 cluster-membership guard
Weaknesses CWE-754
References
Metrics cvssV3_1

{'score': 6.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 7.5, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mongodb
Published
Updated
Nov 10, 2026, 8:06 PM
Reserved
Nov 2, 2026, 10:54 PM
Status
Awaiting Analysis
Published
Nov 10, 2026, 8:18 PM
Modified
Nov 10, 2026, 10:08 PM