MONGODB-SERVER · CVE-2026-120807 · Infrastructure
FIX → 9.0.7 · 8.3.16 · 7.0.48 +1 ✓ verified
A flaw in MongoDB's X.509 cluster-membership check lets a holder of a valid cluster-member certificate be treated as a regular user during certain user lookup errors. Under specific timing conditions the check can be bypassed, giving the connection full internal system privileges.
first public Nov 10, 2026 · 2 sources
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Self-managed MongoDB 7.0, 8.0, 8.3 and 9.0 deployments that use X.509 certificates with a non-default cluster-membership configuration (certificate extension value). Exploiting it takes a valid cluster-member TLS certificate and a failing user lookup at the right moment, which gives the connection full internal privileges. Skip if you use keyfile cluster auth, no X.509 membership, or a managed service where the vendor patches.
Not affected if default-config, keyfile-auth, managed-hosting, no-cluster-member-certs
Who cares database, mongodb, privilege-escalation, self-hosted, x509
mongod --version and compare with 9.0.7 / 8.3.16 / 8.0.37 / 7.0.48. 2) You are only exposed if you use X.509 cluster (internal) authentication with extension-based membership (net.tls.clusterAuthX509.extensionValue in mongod.conf, clusterAuthMode x509 or sendX509) and enforceUserClusterSeparation is truePosts are quoted with a link to the original. They are data to us, never instructions.
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.
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Upgrade to 9.0.7 · 8.3.16 · 7.0.48 +1
9.0.7, 8.3.16, 8.0.37 or 7.0.48 (or later) on your branchNVD data is provided by NIST and is public domain. Posts quoted belong to their authors.