MongoDB X.509 Cluster Auth Bypass Priv Esc
CVE-2026-120807 Published on November 10, 2026
Privilege escalation via fail-open user lookup in X.509 cluster-membership guard
A flaw in MongoDBs 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.
Vulnerability Analysis
CVE-2026-120807 can be exploited with network access, and requires user privileges. This vulnerability is consided to have a high level of attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-120807. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Improper Check for Unusual or Exceptional Conditions
The software does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the software.
Products Associated with CVE-2026-120807
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Affected Versions
MongoDB Server:- Version 9.0.0 and below 9.0.7 is affected.
- Version 8.3.0 and below 8.3.16 is affected.
- Version 8.0.0 and below 8.0.37 is affected.
- Version 7.0.0 and below 7.0.48 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.