Why do bearer tokens create governance problems for machine identity?

Why This Matters for Security Teams

Bearer tokens are attractive because they are simple to issue and easy to pass between services, but that same simplicity creates governance gaps for machine identity. If a token is copied from a log, queue, ticket, or endpoint, any holder can use it until it expires. That means possession becomes authority, with no cryptographic proof that the original workload is still the one presenting it.

For security teams, the real issue is not just theft but control-plane ambiguity: who owns the token, which workload received it, what it can reach, and how fast it can be revoked. The problem shows up frequently in secret sprawl scenarios documented in NHIMG research such as the Guide to the Secret Sprawl Challenge and breach analysis like the JetBrains GitHub plugin token exposure. Current guidance from the NIST Cybersecurity Framework 2.0 still pushes teams toward asset visibility, least privilege, and continuous monitoring, but bearer-token governance fails when those tokens are copied outside the original trust path.

In practice, many security teams encounter bearer-token abuse only after a token has already been reused across multiple systems, rather than through intentional lifecycle control.

How It Works in Practice

The governance problem starts with the token model itself. A bearer token proves that someone has the token, not that a specific workload is still the rightful holder. In machine-to-machine environments, that weak proof is dangerous because workloads are ephemeral, automations are noisy, and tokens often move through CI/CD logs, message brokers, API gateways, and support tooling. NHIMG’s 52 NHI Breaches Analysis and the Ultimate Guide to NHIs show that token exposure is not hypothetical; it is a recurring operational failure.

Better practice is to reduce bearer-token dependence and bind runtime access to workload identity. That usually means cryptographic proof of what the workload is, then short-lived authorization for what it is allowed to do. Common controls include:

• Binding tokens to workload keys or certificates so replayed tokens are not enough on their own.
• Using short TTLs and JIT issuance so the credential exists only for the task window.
• Evaluating access at request time with policy-as-code instead of relying only on static role assignments.
• Tracking issuance, audience, and revocation events for auditability and incident response.

That approach aligns with emerging machine-identity practice and with the direction of zero trust thinking in CISA Zero Trust Maturity Model and workload-centric designs such as SPIFFE, where the workload presents verifiable identity rather than a reusable secret. The main operational shift is that access decisions move from “who has the token” to “what workload is this, what is it trying to do, and is that allowed right now?” These controls tend to break down in legacy batch pipelines and shared service accounts because the same credential is reused across multiple jobs and owners.

Common Variations and Edge Cases

Tighter token controls often increase integration overhead, requiring organisations to balance replay resistance against deployment complexity. There is no universal standard for this yet, so teams need to choose pragmatic patterns based on workload type and blast radius.

Long-lived service accounts are the most obvious edge case because they often exist to avoid operational friction, yet they create the very governance ambiguity bearer tokens already have. Shared runtime platforms, especially where multiple apps reuse the same token, are another weak spot. Entro Security’s 2025 research reported that 60% of NHIs are overused, which reinforces how often one credential ends up serving multiple owners and purposes.

For high-frequency service calls, full certificate binding may be too heavy, so some environments use short-lived OIDC tokens with audience restriction and narrow scopes. For high-risk paths, stronger binding and stricter revocation are usually justified. The current guidance suggests matching credential strength to the sensitivity of the action, not to the convenience of the platform. In practice, bearer tokens remain acceptable only when their lifetime, scope, and exposure path are tightly constrained, and when revocation is automated rather than manual.

Related resources from NHI Mgmt Group

• Why do disconnected IT tools create identity governance problems?
• Why does shadow IT create identity governance risk?
• Why do self-service portals create governance risk in identity programmes?
• Why do complex identity tools create governance risk?