An access token is usually time-limited and meant for immediate API calls, while a refresh token is a longer-lived grant that can obtain new access tokens. The security impact is very different. Losing an access token may be temporary, but losing a refresh token can preserve access until the underlying grant is revoked.
Why This Matters for Security Teams
Short-lived access tokens and refresh tokens are both part of modern authentication, but they create very different risk profiles. An access token usually limits immediate blast radius because it expires quickly and is meant for one task or a short session. A refresh token is more powerful: it can mint new access tokens, so compromise often turns into persistent access until the underlying grant is revoked. That is why token handling belongs in the same control conversation as NHI governance, not just app auth. The risk becomes sharper in environments where secrets are copied into pipelines, chat tools, or agent workflows, as described in the Guide to the Secret Sprawl Challenge and the Salesloft OAuth token breach.
For NHI programmes, the issue is not token type alone but where token reuse, storage, and revocation are weak. The OWASP Non-Human Identity Top 10 and NIST Cybersecurity Framework 2.0 both reinforce the need for lifecycle control, least privilege, and rapid response. In practice, many security teams discover refresh-token risk only after a developer laptop, CI runner, or SaaS integration has already been used to quietly extend access.
How It Works in Practice
Access tokens and refresh tokens solve different problems. An access token is presented to a resource server for API calls and should be narrow in scope, short in lifetime, and easy to invalidate through expiry. A refresh token is typically held by the client or broker and exists to request a new access token without forcing the user or workload to reauthenticate. That convenience is useful, but it means the refresh token becomes the higher-value credential.
In a well-run identity design, the access token is treated as a disposable bearer artefact, while the refresh token is treated more like a standing grant that needs extra protection. Current guidance suggests several practical controls:
- Use the shortest access token lifetime that still supports the workload.
- Store refresh tokens only where strong protection exists, such as a hardened secrets manager or platform-native credential store.
- Bind tokens to specific audiences, clients, or device contexts where possible.
- Revoke the underlying refresh grant immediately when compromise is suspected, not just the active access token.
- Monitor token issuance patterns for unusual reuse, location shifts, or repeated refresh attempts.
This is where NHI visibility matters. The Ultimate Guide to NHIs notes that only 5.7% of organisations have full visibility into their service accounts, which is a useful warning sign for token governance as well. If a team cannot see where tokens live, who refreshes them, and what they unlock, the real risk is not the expiry window but the persistence window. These controls tend to break down in distributed SaaS integrations and CI/CD environments because refresh tokens are copied into too many execution contexts to track reliably.
Common Variations and Edge Cases
Tighter token controls often increase operational overhead, so organisations must balance reduced exposure against developer friction and service reliability. That tradeoff shows up most clearly when tokens are used by headless workloads, partner integrations, or automation that cannot tolerate frequent reauthentication.
One common edge case is token exchange or delegated access, where a refresh token may be replaced by a brokered credential chain. In those designs, the security question shifts from “How long does the access token last?” to “What standing grant can keep reminting access?” Another variation is opaque versus self-contained access tokens. Self-contained tokens can continue to work until expiry even after a server-side event, while refresh token revocation may be the only practical way to stop ongoing renewal.
There is no universal standard for every refresh-token design, especially across mobile apps, browser sessions, and machine-to-machine flows. Best practice is evolving, but the consistent principle is simple: keep refresh capability rarer, better protected, and easier to revoke than the access token it creates. That principle is echoed across the 52 NHI Breaches Analysis and the Top 10 NHI Issues, both of which show how persistent grants and weak lifecycle controls turn a temporary compromise into extended access. For identity risk teams, the practical test is whether revoking the refresh path truly ends access across every connected system.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST CSF 2.0 and NIST Zero Trust (SP 800-207) set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-03 | Token lifetime and revocation are core NHI credential hygiene concerns. |
| NIST CSF 2.0 | PR.AC-4 | Least-privilege access helps limit damage from stolen access or refresh tokens. |
| NIST Zero Trust (SP 800-207) | SC-3 | Zero trust requires verifying each token request, not trusting long-lived grants. |
Evaluate every token refresh with contextual policy and revoke standing trust quickly.
Related resources from NHI Mgmt Group
- What is the difference between short-lived tokens and static API keys for agents?
- When do OAuth refresh tokens become more risky than short-lived access tokens?
- What is the difference between short-lived access and safe access for non-human identities?
- What is the difference between short-lived tokens and CAEP-based enforcement?
