Use a workload identity provider or equivalent broker so local runtime identity can be translated into target-system credentials with policy applied at issuance. That approach preserves centralized governance while still supporting heterogeneous clouds, SaaS platforms, and legacy systems that cannot all trust the same native identity format.
How cross-domain access should be brokered for an AI agent
An AI agent should not carry one trusted identity everywhere. Cross-domain access works best when a local runtime identity is exchanged through a broker or workload identity provider into target-system credentials that are issued with explicit policy. That keeps the agent’s authority narrow, auditable, and adaptable across clouds, SaaS, and legacy systems.
In practice, the broker becomes the control point for translation, scope, and expiry. The agent can authenticate once in its local runtime, but each downstream system should receive credentials that reflect the target system’s own trust model, not an unconstrained copy of the agent’s original token.
That distinction matters because cross-domain access is usually where trust assumptions break. One system may understand federated identity, another may need short-lived API credentials, and a third may still rely on service accounts or delegated secrets. A broker lets teams normalize those differences without letting the agent accumulate standing privilege.
What policy should govern the exchange and the resulting access
The exchange should be policy-led, not convenience-led. Teams should define which agents may request cross-domain access, which actions can be delegated, what conditions must be present, and how long the issued credential may live. The right model is least privilege at issuance, with policy evaluated before the target credential is minted.
That also means separating identity from entitlement. The same agent may be known to several systems, but it should not inherit the same permissions in each one. Target-specific authorization should reflect the task, the environment, and the system being accessed, with explicit boundaries for read, write, admin, and data movement actions.
Where possible, teams should prefer just-in-time issuance over reusable credentials. If the target system can accept a short-lived token, assertion, or scoped session, use that rather than a long-lived secret. A broker is most valuable when it can reduce trust to the smallest possible window and record the reason for the grant.
What this means for architecture, governance, and interoperability
Cross-domain access is an interoperability problem as much as an authorization problem. The broker needs to bridge heterogeneous trust formats without creating a new uncontrolled layer. That usually means support for token exchange, delegated authorization, credential vaulting or signing, plus clear routing to the target system’s native authentication method.
Governance should treat the broker as a sensitive control plane. Its policies, mappings, and logs define what the agent can do across environments, so changes to translation rules are security changes, not just configuration updates. This is where teams should apply AI Agent Authorisation Guide principles around task-scoped access, per-action policy, and human approval for higher-risk operations.
For teams formalising the agent identity layer, Agentic AI Identity Guide is useful because it frames registration, delegation, ownership, and retirement as part of the same lifecycle, rather than treating cross-domain access as an ad hoc integration problem. When access spans many systems, lifecycle discipline becomes the difference between controlled delegation and credential sprawl.
If your environment already struggles with shared sessions or browser-based delegation, Browser and Computer-Use Agent Security Guide is a good reminder that the agent should not be allowed to reuse ambient human access when a brokered, bounded path is available.
Risk and Threat Considerations
Cross-domain access increases blast radius because one compromised agent or broker path can bridge otherwise separate trust zones. The main risk is not that the agent has access, but that it can turn one valid foothold into broad movement across systems that were never meant to share the same credential format or privilege model.
Failure mechanism: The broker issues credentials that are too broad, too long-lived, or too reusable, or it translates a local identity into target access without enforcing a fresh policy decision for the specific request. An attacker who steals the runtime identity, interception point, or issued credential can then pivot into multiple domains through a trust path that looks legitimate.
Impact: Excessive cross-domain trust can lead to unauthorized data access, destructive actions in downstream systems, and difficult attribution because each target system sees a valid credential rather than an obviously suspicious source. At scale, poor translation controls also make revocation and incident containment slower, especially when a single agent interacts with cloud services, SaaS tools, and legacy platforms.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Agentic AI Top 10 addresses the attack and risk surface, while NIST SP 800-53 Rev 5 and NIST Zero Trust (SP 800-207) set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | Cross-domain agent access hinges on controlling delegated privilege and preventing overbroad authority. |
| Recommendation — Enforce per-action authorization and limit each agent to the minimum privilege needed for the target domain. | ||
| NIST SP 800-53 Rev 5 | IA-9 — Service Identification and Authentication | Brokered cross-domain access is about authenticating non-human workloads to each other. |
| AC-6 — Least Privilege | The answer depends on issuing the narrowest feasible target-system access at runtime. | |
| IA-5 — Authenticator Management | Brokered access depends on managing issued secrets, tokens, and credential lifetimes safely. | |
| Recommendation — Use service-to-service authentication and short-lived credentials for each target system. Grant only the target permissions required for the current task and revoke them after use. Issue, rotate, and expire downstream credentials under central control. | ||
| NIST Zero Trust (SP 800-207) | JIT — Just-in-Time Access | Cross-domain agent access should be time-bounded and policy-driven rather than standing. |
| Recommendation — Deliver access only when needed and remove it immediately after the task completes. | ||
Practitioner Guidance
What to verify: Verify that each target system receives a separately scoped credential or assertion, not a copied source token with broader reach. Confirm that the broker evaluates policy at issuance, logs the decision context, and can distinguish read-only access from any action that changes state.
Decision rule: If the target system cannot accept short-lived, policy-bound access, treat that integration as higher risk and require compensating controls such as stricter segmentation, tighter approval gates, or reduced agent capability. Do not let operational convenience drive the trust model.
What good looks like: The agent can complete the task without retaining standing privilege, downstream systems can see who or what actually acted, and revocation of the brokered path reliably cuts off future access without breaking unrelated services.
Practitioner takeaway: The goal is not to make every system trust the same agent identity, it is to let a controlled broker translate intent into the smallest safe credential for each domain.
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Reviewed and updated by the NHIMG editorial team on October 6, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org