CVE-2024-1248
Summary
by MITRE • 07/04/2026
The silent Just-In-Time (JIT) provisioning feature in federated authentication implementations fails to properly segregate user roles during account creation when a federated user shares a username with a local user. This allows the provisioning process to overwrite existing roles of local users with roles assigned to the federated user.
Exploitation requires a federated identity provider (IDP) with silent JIT provisioning enabled and an attacker's knowledge of a local user's username. When these conditions are met, a malicious individual can leverage the JIT provisioning process to modify the roles of local users. The overwritten roles are limited to those defined within the federated IDP, typically granting minimal access rights unless explicitly configured otherwise by the federated IDP administrator.
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Analysis
by VulDB Data Team • 07/04/2026
The vulnerability described represents a critical access control flaw in federated authentication systems that stems from improper role segregation during just-in-time user provisioning. This issue manifests when federated identity providers implement silent JIT provisioning without adequate safeguards to distinguish between local and federated users who happen to share identical usernames. The root cause lies in the failure of the authentication system to maintain proper user context separation, creating an environment where legitimate local user accounts can be silently modified by federated authentication processes. This vulnerability directly relates to cwe-284 which addresses improper access control and aligns with attack techniques documented under mitre att&ck tactic initial access and privilege escalation through credential access and defense evasion.
The technical implementation flaw occurs at the user provisioning stage where the system fails to verify whether an incoming federated user's username already exists as a local account. When a federated authentication flow triggers JIT provisioning for a user whose username matches an existing local account, the system automatically overwrites the local user's role assignments with those defined in the federated identity provider. This process bypasses normal access control checks and privilege validation mechanisms that should prevent such cross-account modifications. The vulnerability is particularly dangerous because it operates silently without generating audit logs or alerting administrators to the unauthorized modification of existing user permissions, making detection extremely difficult.
The operational impact of this vulnerability extends beyond simple role manipulation to potentially enable privilege escalation attacks. An attacker who discovers a local username can exploit this flaw to modify the access rights of legitimate users within the system, potentially elevating their privileges to administrative levels if the federated IDP is configured with elevated permissions. This creates a vector for lateral movement and persistent access within the network, as the modified local accounts retain their existing authentication context while gaining new capabilities. The limited scope of role overwrites typically restricts immediate damage but provides attackers with opportunities to gradually increase their access privileges through multiple exploitation attempts.
Mitigation strategies must address both the immediate technical flaw and implement comprehensive monitoring controls. Organizations should disable silent JIT provisioning for federated users or implement strict username validation processes that prevent federated authentication from modifying existing local accounts. The recommended approach involves implementing a user account mapping system that creates unique identifiers for federated users rather than allowing direct username matching with local accounts. Additionally, organizations must establish robust audit logging mechanisms that track role modifications and user provisioning events, ensuring that any unauthorized changes to local user permissions are immediately detected and reported. Security controls should also include mandatory review processes for federated user account creation and regular privilege audits to identify potential unauthorized role assignments.