Workload identity proves which agent instance is acting, while delegated user authority determines what that agent may do on behalf of a person or tenant. The first is runtime attestation, the second is business authorization, and they should never be collapsed into one control.
Why this is a control boundary, not just a wording choice
Agent workload identity and delegated user authority solve different security problems. Workload identity answers, “Which agent instance is this?” Delegated user authority answers, “What may that agent do for this user or tenant?” Keeping them separate preserves traceability, prevents overbroad assumptions, and avoids granting an agent more power than the user session actually supports.
That distinction matters because the same agent can be authenticated as a workload while still having highly constrained, user-scoped permissions. The runtime identity is about attestation and trust in the executing agent; the delegated authority is about the business action boundary, consent, and policy that govern on-behalf-of execution.
In practice, the clean split is what lets teams reason about provenance, session scope, and approval independently. An agent may be genuine and still not be entitled to act on a sensitive record, and an agent may be allowed to complete a task without being allowed to reuse the user's broader privileges.
How workload identity and delegated authority differ in the security model
Workload identity is the mechanism that binds an agent process, workload, or service instance to a cryptographic or platform-backed identity at runtime. It is used for authentication, trust establishment, and often service-to-service access. The question it answers is operational: does this running agent really present the expected identity, environment, or attestation state?
Delegated user authority is an authorization construct. It determines whether the agent is allowed to act on behalf of a person, application, or tenant, and under what constraints. That can involve token exchange, consent, scoped delegation, impersonation limits, or a policy decision that says the agent may read one mailbox, submit one transaction, or invoke one tool, but nothing broader.
These are not interchangeable. A valid workload identity does not automatically create delegated permission, and delegated permission should not be inferred from the presence of a valid workload credential. Conflating the two is how teams end up with agents that are trusted to run but not properly bounded in what they can do.
Where the boundary usually breaks in real deployments
The boundary tends to fail when engineers use the workload credential as if it were the business authorization signal. That creates a shortcut where any authenticated agent is treated as if it inherited the user's intent, scopes, or tenant privileges. The result is usually privilege inflation, ambiguous accountability, or hidden cross-tenant reach.
Another common failure is collapsing delegation into static role assignment. If the agent gets a standing role because it needs to act for users, then the runtime identity and the delegated authority become fused, and revocation becomes coarse. That is especially risky when the agent operates across multiple tools or data sources with different sensitivity levels.
For agent systems that use token exchange or on-behalf-of flows, the safest interpretation is that the workload identity proves the caller, while the delegated artifact proves the user's bounded authorization. One answers who is speaking; the other answers what authority was transferred for this specific action.
Risk and Threat Considerations
Mixing workload identity and delegated user authority creates a privilege boundary problem. If the agent's runtime identity is treated as sufficient proof of user authority, an attacker who compromises the agent, its token, or its execution environment can often expand access beyond the intended user scope.
Failure mechanism: The platform accepts a valid workload credential as a proxy for delegated consent or business authorization, so a compromised or over-privileged agent can reuse trust intended only for authenticated execution, not for user-level action.
Impact: This can lead to unauthorized reads, writes, transactions, or cross-tenant actions, and it makes incident response harder because logs may show a legitimate agent identity even when the action was not properly authorized on behalf of the user.
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 and OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST SP 800-53 Rev 5 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | Agent identity and delegated authority must be separated to prevent privilege inflation. |
| Recommendation — Separate workload authentication from delegated authorization and limit agent privileges to each scoped action. | ||
| OWASP Non-Human Identity Top 10 | NHI-04 — Insecure Authentication | Workload identity is the authentication side of the split between agent and delegation. |
| Recommendation — Use strong workload authentication so agent instances are verified before any delegated action is considered. | ||
| NIST SP 800-53 Rev 5 | IA-9 — Identification and Authentication (Service and Application Accounts) | Agent workloads need their own authentication boundary distinct from user-authorized actions. |
| AC-3 — Access Enforcement | Delegated user authority is enforced by access rules that limit what the agent may do. | |
| Recommendation — Authenticate the agent as a service or application account before evaluating delegated permissions. Enforce action-specific authorization so delegated scopes cannot expand into broader user rights. | ||
Practitioner Guidance
What to verify: Confirm that your control plane records both the workload identity and the delegated authority artifact separately, with distinct expiry, audience, and scope semantics. If you cannot independently revoke one without breaking the other, the design is too coupled.
Decision rule: If the agent must act across user context, require explicit delegated scopes or token exchange for each business action class; if it only needs machine-to-machine access, keep it on workload identity alone and do not add user delegation by default.
Common mistake: Treating “the agent authenticated successfully” as equivalent to “the agent is authorised to act for the user.” Those are different trust decisions, and they should be audited, logged, and reviewed separately.
Practitioner takeaway: Build for two proofs, not one: the agent must prove who it is as a workload, and separately prove what authority it has inherited for the current user-bound action.
Related resources from NHI Mgmt Group
- What is the difference between human identity governance and AI agent governance?
- What is the difference between workload identity and API keys for AI agents?
- What is the difference between governing human access and governing AI agent access?
- What is the difference between workload identity and agent identity?
Deepen Your Knowledge
Free weekly newsletter
Subscribe to the NHI & AI Identity Journal
The latest on NHI and Agentic AI security – articles, research, breaches, news and events every week.
Bonus 33% off our NHI Course when you subscribe.
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