What happens when a delegated AI agent is started by a user whose session ends or whose access is revoked?

When the underlying user session ends, delegated refreshes are refused and the agent stops renewing access. If the session is revoked, the refresh token, every access token issued from it, and any chained sessions are invalidated. That makes revocation cascade through the whole session chain instead of leaving a residual window for continued agent activity.

When a Delegated Agent Inherits a User Session

A delegated AI agent is only as durable as the user context that authorises it. If the user’s session expires, the agent should lose the ability to renew credentials and continue acting; if access is revoked, the revocation should cascade through the issued tokens and any chained sessions. That matters because delegated agents often sit between a human approval moment and later autonomous execution, so the control boundary is the session lifecycle rather than the initial launch event.

This is why session binding, token freshness, and revocation propagation are not administrative details. They define whether the agent is still operating within a legitimate trust window or merely continuing on leftover authority. For security teams, the important distinction is between a tool that pauses cleanly when the user context disappears and one that can keep moving with stale rights. In practice, many failures are discovered only after an agent has already continued beyond the user’s intended control window.

How Session Ending and Revocation Actually Work

In a delegated model, the agent usually does not hold permanent standing privilege. Instead, it relies on a user-approved chain of credentials, often starting with a refresh token or similar delegated grant. While the user session remains valid, the agent can request new access tokens or continue a bounded workflow. Once the session ends, the refresh path should fail, which prevents the agent from extending its access beyond that session’s lifetime.

Revocation is stronger than expiry. When access is revoked, the system should invalidate the refresh token, any access tokens derived from it, and any linked or chained sessions that inherit from the original grant. That prevents a residual execution window where the agent keeps calling downstream services even though the originating user no longer has authority. The control objective is not just logout behaviour; it is stopping the entire delegated trust chain from being used as a proxy for the revoked user.

This becomes especially important for agents that can fan out into other tools, APIs, or long-running workflows. A well-designed implementation checks token validity at renewal time, respects revocation lists or back-channel logout signals where available, and treats the user session as the source of truth for continued delegation. Where the platform only checks access at launch time, revocation may not meaningfully stop execution until the current token naturally expires. The practical risk is that the agent appears “logged in” to downstream systems after the user is no longer authorised.

Session expiry should stop renewal, not merely mark the user as inactive.
Revocation should invalidate the full token chain, not only the most recent token.
Long-running jobs need a recheck point if they can outlive the original session.
Audit records should show when delegation was granted, renewed, and terminated.

For agentic systems, the strongest external reference is the OWASP Top 10 for Agentic Applications 2026, because it focuses on the failure modes that emerge once autonomous software starts acting on delegated authority. NHIMG’s own OWASP Agentic Applications Top 10 also maps the same concern to real-world agent behaviour, where token continuity can outlive the user’s intended control window. These controls tend to break down when agents are distributed across multiple services that cache session state independently, because revocation no longer has a single place to land.

Common Variations and Edge Cases

Tighter delegation controls often reduce workflow convenience, so organisations have to balance uninterrupted automation against fast cut-off when authority changes. The main edge case is a long-running agent task that was legitimately started under a valid session but continues after that session ends; best practice is evolving, but current guidance suggests treating any continued renewal attempt as a policy event, not a harmless retry.

Another variation is partial revocation. Some environments revoke the web session but leave API grants, device-bound tokens, or cached downstream credentials intact. That creates inconsistent enforcement, because the user looks signed out in one control plane while the agent still functions in another. Where the agent spans SaaS tools, custom APIs, and intermediate orchestration layers, the revocation design has to cover all of them or the user’s effective authority persists in fragments.

For high-risk workflows, practitioners should assume that any token capable of re-establishing access is part of the delegated chain. The operational question is not whether the agent can keep working briefly, but whether that continuation is still attributable to an active and valid user grant. If the answer is unclear, the environment is relying on expiry timing rather than enforceable revocation.

Risk and Threat Considerations

Delegated agents create a material access-control risk when session end and revocation are not propagated across the full credential chain. The exposure is a residual authority window in which the agent can continue reading data, calling tools, or completing actions after the user is no longer authorised.

Failure mechanism: The weakness usually appears when renewal checks are only enforced at token minting time, while cached access tokens, chained sessions, or downstream service sessions remain valid until they expire naturally. An attacker who compromises the active delegated session can also exploit the same trust chain to persist longer than the originating user intended.

Impact: Sensitive actions may continue after revocation, audit trails become misleading, and downstream systems may accept agent activity that should have been terminated. In a compromised session, that can extend data exposure, preserve unauthorised access, and make containment slower because the agent still appears to hold legitimate delegated authority.

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, OWASP Non-Human Identity Top 10 and CSA MAESTRO address the attack and risk surface, while NIST AI RMF 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	A1 — Excessive Agency	Delegated agents can keep acting after authority should end.
Recommendation — Bind agent action windows to live user authority and stop renewal when delegation ends.
OWASP Non-Human Identity Top 10	NHI-04 — Lifecycle and Revocation	Revocation must cascade through delegated tokens and chained sessions.
Recommendation — Invalidate refresh, access, and chained sessions together when user access is revoked.
CSA MAESTRO	GOV-02 — Governed Agentic Access	Agent governance must define how delegated access is terminated and bounded.
Recommendation — Enforce session-bound delegation rules and require explicit termination semantics for agents.
NIST AI RMF	GOVERN — Govern	Governance should define policy for session-bound delegated AI access and revocation.
Recommendation — Establish governance rules that require delegated AI access to end with the user session.
NIST Zero Trust (SP 800-207)	SC-10 — Validating Device and User States	Continuous validation is needed so revoked user state stops further agent access.
Recommendation — Revalidate user state before renewing delegated access and deny when the session is no longer valid.

Practitioner Guidance

What to verify: Confirm that revocation actually reaches every layer that can renew or reuse delegated authority, including refresh tokens, cached access tokens, and chained sessions. If any component can continue independently of the user session, treat it as an exception that needs explicit expiry or kill-switch handling.

Decision rule: If the agent can perform materially sensitive actions, require a live renewal check before each new access window rather than trusting the original launch approval. If the workflow cannot tolerate that interruption, classify it as higher risk and narrow the agent’s privileges instead of extending token lifetime.

What practitioners underestimate: The hardest failures are not immediate compromise but silent overrun, where the agent continues successfully after the user has left. The control objective is not simply to end a login; it is to make sure no delegated action survives the authority that created it.

Practitioner takeaway: Delegated agents should fail closed with the user session, because any surviving renewal path becomes a hidden extension of human authority.