CVE-2026-120807
Privilege escalation via fail-open user lookup in X.509 cluster-membership guard
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Privilege escalation via fail-open user lookup in X.509 cluster-membership guard
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.
- Record
CVE-2026-120807- CVSS 4.0
- 7.5 High
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 - CVSS 3.1
- 6.6 Medium
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-754
- Updated
- 2026-11-10
EUVDEUVD-2026-122890
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.
- Record
EUVD-2026-122890- CVSS 4.0
- 7.5 High
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 - Updated
- 2026-11-11
GitHub AdvisoriesGHSA-6c5q-2vf6-gqj4
A flaw in MongoDB’s X.509 cluster-membership authentication guard could allow a holder of a...
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.
- Record
GHSA-6c5q-2vf6-gqj4- CVSS 4.0
- 7.5 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.6 Medium
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-754
- Updated
- 2026-11-10
NVD
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.
- Record
CVE-2026-120807- CVSS 4.0
- 7.5 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.6 Medium
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-754
- Updated
- 2026-11-10
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| published | EUVD | |
| published | EUVD | |
| products, severity, title | CVE List, NVD | |
| aliases, cwes, references, severity, title | GitHub Advisories | |
| first indexed | EUVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-120807 is a high vulnerability (CVSS 7.5) in Mongodb Server, published November 10, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.23%, the 13th percentile. No source names a fixed version.