Because the user does not need to trigger the disclosure. When an assistant or agent can surface sensitive information through normal retrieval or rendering, classic user-intent controls do not apply. Security teams need to govern retrieval scope, output handling, and delegation boundaries as part of access control.
Why zero-click leaks are different from ordinary data exposure
Zero-click leaks are higher risk because disclosure happens without the user doing anything wrong or even noticing. That removes the normal guardrails of user intent, approval, and visible interaction, so sensitive content can surface through retrieval, summarisation, or rendering paths that are already trusted by the system.
Ordinary data exposure usually depends on someone opening a file, querying a record, or following a link. Zero-click leakage collapses that trigger step, which means the boundary you need to defend is not just the data store, but the assistant’s context, response generation, and any upstream retrieval source feeding it.
In practice, this shifts the problem from “who can access the data” to “what the system can infer, assemble, or disclose on behalf of a user.” That is why the control set must include output filtering, retrieval scope design, and delegation limits, not just traditional access checks.
Where the risk comes from in assistant and agent workflows
The main risk is that trusted automation can become a disclosure path. If an assistant can search broadly, summarise aggressively, or preserve conversation context across boundaries, it may expose data that no user explicitly requested, especially when hidden instructions, cross-tenant content, or stale context are present.
Zero-click behaviour also increases blast radius. One poisoned prompt, one overly broad retrieval policy, or one poorly isolated tool can expose information across many sessions, channels, or connected systems before anyone notices. A relevant example is EchoLeak (Microsoft 365 Copilot) 2025, which shows how a crafted message can make an assistant leak context without a click.
That makes the failure mode more serious than a conventional accidental share. The system itself can become the delivery mechanism, which means the security question is not only whether data is protected at rest, but whether the assistant is authorised to surface it in the first place.
What practitioners should govern first
Start with the retrieval boundary. If an assistant can reach sensitive sources, the safest design is to narrow what it can retrieve, not rely on downstream content moderation to catch everything after the fact. Retrieval scope should be explicit, reviewable, and tied to the user, session, and task.
Next, treat output handling as a control surface. Sensitive content can leak through snippets, summaries, citations, or even metadata, so teams should define what may be returned, redacted, or withheld before the response is generated. This is especially important when the assistant blends multiple sources into a single answer.
Finally, delegate only the minimum authority needed for the workflow. If the assistant can act across systems, its permissions should be bounded so a disclosure event does not automatically become a broader access event. The issue is not just secrecy, it is preventing unintended authority from being amplified by automation.
Risk and Threat Considerations
Zero-click leaks are risky because they combine hidden triggering conditions with trusted execution paths. An attacker may only need to place malicious or sensitive content where the assistant will ingest it, then let normal retrieval or generation do the rest.
Failure mechanism: The assistant processes content that looks legitimate to the system, but its retrieval, context, or response logic causes sensitive material to be surfaced without a user action that would normally interrupt or validate the disclosure path.
Impact: Sensitive data can be disclosed at scale, across sessions or tenants, with poor auditability and weak user awareness. The result is a larger blast radius than a standard exposure event, because the trusted assistant becomes the exposure mechanism.
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 OWASP API Security 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 | Zero-click leaks often depend on excessive agent authority and context use. |
| Recommendation — Constrain agent authority so it cannot disclose or act beyond the task scope. | ||
| OWASP Non-Human Identity Top 10 | NHI-05 — Overprivileged NHI | Assistant and agent workflows can leak data when their access exceeds need-to-know. |
| NHI-10 — Human Use of NHI | Human-driven tasks can accidentally route sensitive data through automated assistants. | |
| Recommendation — Reduce NHI privileges to the minimum needed for retrieval and response generation. Prevent humans from using non-human access paths to bypass disclosure controls. | ||
| NIST SP 800-53 Rev 5 | AC-6 — Least Privilege | The answer centers on limiting assistant authority and disclosure paths. |
| IA-9 — Identification and Authentication (Non-Organizational Users) | Assistant and service interactions depend on authenticated non-human access paths. | |
| AU-2 — Event Logging | Zero-click disclosure needs visibility into what the assistant retrieved and emitted. | |
| Recommendation — Apply least privilege to retrieval, context access, and output generation paths. Authenticate non-human access paths before allowing data retrieval or output. Log retrieval, context use, and disclosure events for later investigation. | ||
| OWASP API Security Top 10 | API6 — Unrestricted Access to Sensitive Business Flows | Assistant workflows can expose sensitive business data without the user's explicit action. |
| Recommendation — Restrict automated flows that can reveal sensitive data without strong checks. | ||
Practitioner Guidance
What to verify: Verify which sources the assistant can retrieve from, which fields it can render, and whether sensitive context can persist beyond the task that created it. If you cannot explain the full disclosure path, you do not yet have a reliable control design.
Decision rule: If the assistant can surface data that the user did not explicitly request, treat that as a governance issue, not just a content-safety issue. Reduce retrieval scope and delegation first, then tune filters and review workflows.
What practitioners underestimate: The most dangerous leaks are often the ones that look like normal product behaviour. If the output appears “helpful,” teams may miss that the system has crossed a privilege boundary on the user’s behalf.
Practitioner takeaway: Zero-click leaks are more dangerous than ordinary exposure because they invalidate user-intent assumptions, so the control objective is to bound what the assistant can retrieve, retain, and disclose by default.