CVE-2026-18691

CRITICAL CVSS 4.0: 9.0 EPSS 0.23%
Updated Aug 12, 2026
MongoDB
Parameter Value
CVSS 9.0 (CRITICAL)
Type CWE-757
Vendor MongoDB
Public PoC No

An issue in MongoDB Server's intra-cluster connection setup could allow a party with suitable network access to influence which authentication mechanism is used when one replica set member connects to another. Under certain conditions, this could cause the cluster's shared internal credential to be transmitted in a less-protected form, potentially allowing that credential to be recovered. If recovered, the credential could be used to authenticate as the internal superuser to nodes in the deployment.

Attack Parameters

Attack Vector
Adjacent
Requires local network access
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Weakness Type (CWE)