CVE-2025-10149 in Identity Server as Key Manager
Summary
by MITRE • 10/19/2026
The SCIM endpoint does not sufficiently validate authorization for federated users when performing operations against the local user store. This occurs when a local and a federated user share the same username, allowing a federated user to perform actions intended for a local user, including arbitrary operations.
A malicious actor authenticated as a federated user may perform arbitrary operations on local user accounts via the SCIM 2.0 or SCIM 1.1 endpoints when local and federated users share the same username. This could lead to user account takeover. Deployments that do not support user self-registration are considered medium severity.
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Analysis
by VulDB Data Team • 10/23/2026
The vulnerability described involves a critical authorization flaw within the System for Cross-domain Identity Management SCIM endpoint, specifically affecting environments where local and federated identity providers coexist. The core technical issue stems from insufficient validation of authorization contexts when operations target the local user store. In systems that support both native local accounts and external federated identities through protocols such as SAML or OAuth, there exists a potential for username collision if identical usernames are provisioned in both directories. When this overlap occurs, the SCIM service fails to correctly distinguish between the authentication context of the requesting entity and the identity store being targeted. Consequently, an attacker authenticated via federation can exploit this ambiguity by specifying operations that reference local user accounts sharing their federated username. This logic error allows the malicious actor to bypass intended access controls, effectively treating a local account as if it were under their direct control or authorized scope.
From a technical perspective, this flaw represents a classic case of improper privilege assignment due to ambiguous identity resolution. The SCIM API endpoints for versions 1.1 and 2.0 are designed to manage user resources across domains, but the implementation lacks robust checks to ensure that the authenticated session's domain matches the target resource's domain when usernames collide. This oversight enables arbitrary operations on local user accounts, which may include modifying account attributes, resetting passwords, or altering group memberships depending on the specific API methods exposed and their default permissions. The ability to perform these actions without proper authorization constitutes a severe breach of integrity and confidentiality within the identity management infrastructure.
The operational impact of this vulnerability is significant, primarily centering on user account takeover. An authenticated malicious actor can leverage this flaw to assume the identity of local users who share usernames with federated accounts. This capability allows for unauthorized access to applications protected by these local accounts, potentially leading to data exfiltration, lateral movement within the network, or further privilege escalation if those local accounts possess administrative rights. The severity is rated as medium in deployments that do not support user self-registration because the attack requires an existing authenticated session and a specific username collision scenario. However, even with this constraint, the ability to manipulate local account configurations poses a substantial risk to organizational security posture by undermining the separation of duties between federated and native identity sources.
To mitigate this vulnerability, organizations must implement strict namespace isolation or unique naming conventions that prevent any overlap between local usernames and federated identities. This can be achieved through technical controls such as appending domain suffixes to all user identifiers during provisioning, ensuring that no two users across different identity stores share the same principal name. Additionally, access control lists should be hardened to explicitly verify the origin of the authenticated session against the target resource's storage location before executing any write operations. Regular audits of user directories can help identify existing collisions that need remediation. From a standards perspective, this issue aligns with CWE-269 Improper Privilege Assignment and relates to ATT&CK techniques involving account manipulation and privilege escalation within identity management systems. Ensuring robust validation logic in SCIM implementations is essential to maintain the integrity of hybrid identity environments.