CVE-2026-118426 in Octopus Server
Summary
by MITRE • 10/29/2026
In affected versions of Octopus Server with the LDAP authentication provider enabled, any authenticated user could call the LDAP user search and LDAP group search.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/29/2026
The vulnerability identified in Octopus Server involves a critical authorization flaw within the Lightweight Directory Access Protocol (LDAP) integration module. When the LDAP authentication provider is enabled for managing user identities and access control, the system fails to enforce proper role-based access controls on specific administrative endpoints related to directory services. Specifically, the API endpoints responsible for performing LDAP user searches and group searches are accessible to any authenticated session, regardless of whether that session belongs to an administrator or a standard end-user with limited privileges. This misconfiguration represents a breakdown in the principle of least privilege, allowing lower-privileged actors to execute queries against the connected directory service without sufficient verification of their authority to do so.
From a technical perspective, this flaw constitutes an Insecure Direct Object Reference (IDOR) combined with Broken Access Control vulnerabilities as defined by the Common Weakness Enumeration standards under CWE-639 and CWE-284 respectively. The application logic assumes that because a user has successfully authenticated via LDAP or another provider, they possess implicit rights to query directory metadata. However, searching for users and groups is typically an administrative function intended to assist system administrators in managing permissions, auditing access, or configuring role mappings. By exposing these search capabilities to all authenticated users, the server inadvertently leaks internal organizational structure data that should remain restricted.
The operational impact of this vulnerability extends beyond simple information disclosure. An attacker with a low-privileged account can enumerate valid usernames and group memberships within the organization's Active Directory or LDAP directory. This reconnaissance phase is highly valuable for subsequent attack vectors such as credential stuffing, targeted phishing campaigns known as spear-phishing, or privilege escalation attempts. By knowing which users belong to specific administrative groups, an adversary can tailor their social engineering attacks more effectively or identify high-value targets for further exploitation. Furthermore, the ability to search group memberships may reveal sensitive organizational hierarchies and operational structures that are considered confidential intellectual property or security-sensitive information.
This behavior aligns with several tactics in the MITRE ATT&CK framework, particularly those related to Discovery and Credential Access. The unauthorized enumeration of user accounts maps directly to T1087 Account Discovery, where adversaries gather information about system users and groups to facilitate lateral movement or privilege escalation. Additionally, if this data is used to identify high-privilege accounts for targeted attacks, it supports the T1526 Cloud Service Discovery tactic when integrated with cloud-based identity providers. The lack of proper authorization checks on these endpoints allows an attacker to pivot from a low-level foothold into deeper reconnaissance phases without triggering typical anomaly detection systems that monitor administrative actions rather than user-initiated queries.
To mitigate this risk, immediate remediation is required by applying the vendor-provided patch or update for Octopus Server versions affected by this issue. Administrators should verify their current version and upgrade to a release where access controls on LDAP search endpoints are strictly enforced to allow only users with explicit administrative roles. In environments where upgrading is not immediately feasible, network-level mitigations such as restricting API endpoint access via firewall rules or reverse proxy configurations can provide temporary relief by limiting exposure to trusted internal subnets. Additionally, implementing robust logging and monitoring for unusual patterns of LDAP search queries from non-administrative accounts can help detect potential exploitation attempts in real-time. Regular audits of authentication provider configurations and strict adherence to role-based access control policies are essential preventive measures against similar authorization bypass vulnerabilities.