API security vulnerabilities are becoming an identity governance problem

At a glance

What this is: NHI Mgmt Group's analysis, drawing on Raidiam's blog post: API security failures increasingly reflect identity governance gaps, especially where bearer tokens, third-party integrations, and incomplete API inventories leave access decisions too weak to control.

Why it matters: For IAM, IGA, and API security teams, the issue is no longer only protecting endpoints, but governing who and what can obtain, present, and reuse API access across ecosystems.

By the numbers:

• 84% of security professionals experienced an API security incident in the past year.
• 92% of organisations using APIs suffered a breach within the last 12 months.
• API-related vulnerabilities are now costing organisations up to $87 billion annually.

Context

APIs are the control points where applications, partners, and services exchange data and authorise actions. When those access paths rely on bearer tokens, incomplete inventories, or weak third-party oversight, the problem becomes one of identity governance as much as application security.

Raidiam’s article frames API vulnerability management as a board-level issue because the blast radius is not limited to one application. The real governance gap is that many organisations cannot reliably see which APIs exist, what data they expose, or which external parties can reach them.

That makes API security a lifecycle problem across authentication, authorisation, inventory, and partner access. For IAM teams, the question is whether API access is governed as an identity estate or treated as a set of disconnected technical integrations.

Key questions

Q: What breaks when API security relies on bearer tokens alone?

A: Bearer-only API security breaks when a token can be intercepted and replayed by anyone who possesses it. That means the token no longer proves the sender’s identity, only possession. In practice, this increases the value of logs, proxies, and compromised endpoints as replay sources, and it makes token binding or sender-constrained designs much more important for high-risk APIs.

Q: Why do third-party API calls create identity governance risk?

A: Because they move sensitive data and delegated authority outside the control points that IAM teams usually monitor. When internal workloads call external APIs directly, the organisation may lose visibility into authentication context, logging, and downstream handling. That makes service account scope, token lifecycle, and outbound monitoring central governance controls.

Q: How can teams tell whether API governance is actually working?

A: A working programme can answer four questions quickly: who owns the consumer, what it can access, where the policy is enforced, and how the call is logged. If any of those answers differ across protocols or gateways, the control model is fragmented and needs consolidation.

Q: What is the difference between API discovery and API governance?

A: API discovery finds what exists, while API governance decides who may use it, how it may be accessed, and when that access must be removed. Discovery is the visibility layer; governance is the control layer. Organisations need both, because you cannot enforce policy on interfaces you have not found.

Technical breakdown

Bearer tokens and why they create governance fragility

Bearer tokens authenticate by possession, not by a bound proof of identity. That means anyone who intercepts or reuses the token can present it to the API unless additional controls, such as sender-constrained mechanisms, are in place. In identity terms, the token often becomes a transferable credential with unclear ownership, limited audience restriction, and weak lifecycle control. That is why API security cannot be reduced to encryption or perimeter protection alone. The security question is whether the token can be reused outside the intended trust context.

Practical implication: treat bearer-token use as a governance risk and define where token possession is no longer sufficient for access.

Third-party API integrations and inherited trust

Modern API ecosystems are rarely single-owner environments. Third-party integrations, partner connections, and delegated access expand the trust boundary beyond the enterprise, often without the same lifecycle discipline applied to internal accounts. When partner access is not inventoried, reviewed, and revoked consistently, API exposure becomes an access-governance problem rather than a pure application flaw. The article’s emphasis on supply chain vulnerabilities reflects this broader reality: the weakest identity control may sit outside your direct administrative boundary. That changes the role of IAM from internal control to ecosystem governance.

Practical implication: map third-party API access as governed external identity rather than informal technical integration.

API inventory gaps hide unauthorised access paths

An API inventory is not just a documentation exercise. It is the prerequisite for understanding which systems can exchange sensitive data, which authentication patterns they use, and where insecure protocols remain in production. Without that inventory, teams cannot enforce consistent policy, detect shadow integrations, or know which APIs still rely on outdated trust assumptions. The article notes that many organisations lack this visibility, which means they are operating with partial control over their identity surface. In practice, discovery is a governance control, not a reporting task.

Practical implication: establish authoritative API discovery so every exposed interface is tied to ownership, policy, and review.

Threat narrative

Attacker objective: The objective is to obtain unauthorised API access that can be used to steal data, impersonate trusted services, or abuse connected business functions.

1. Entry occurs when attackers exploit weak credential handling, intercepted tokens, or exposed third-party API paths to reach protected interfaces.
2. Escalation follows when those credentials or tokens are accepted as sufficient proof of access, allowing the attacker to impersonate a legitimate caller.
3. Impact occurs when the attacker uses that API trust to access sensitive data, manipulate business flows, or extend compromise into connected systems.

Breaches seen in the wild

• T-Mobile API breach 2023: An attacker pulled data on 37 million T-Mobile accounts through one API, without authorisation, for six weeks before detection.
• Sourcegraph breach 2023: A site-admin token left in a Sourcegraph commit for 47 days let an attacker become admin and offer free access to its APIs and LLM via a proxy.

Read and download The State of NHI & AI Agent Breach Report 2026, covering 200+ breaches impacting Non-Human Identities including AI Agents.

NHI Mgmt Group analysis

API security is now an identity governance problem, not just an application control problem. The article is right to shift the frame from endpoint protection to access governance because bearer tokens, partner integrations, and incomplete inventories all determine who can act through an API. That means the real control plane is the identity relationship behind the call, not the request itself. Practitioners should treat API access as governed identity activity across issuance, scope, and revocation.

Bearer-token trust is a weak governance assumption because possession is not proof of legitimacy. APIs that accept possession alone are built on the assumption that the token will remain private and context-bound. Once that assumption fails, the identity model becomes transferable and the boundary between authorised and unauthorised use collapses. Practitioners should re-evaluate where bearer semantics still exist in high-value API paths.

Third-party API access expands the identity perimeter beyond what most IAM programmes can currently supervise. The article’s supply chain emphasis reflects a practical truth: partner access often receives lighter lifecycle scrutiny than internal user or service access. That creates a persistence problem, because external integrations outlive the business relationship that justified them. Practitioners should govern partner APIs with the same inventory, ownership, and offboarding expectations used for sensitive internal access.

API inventory is the named concept that separates visibility from control. The article shows that many organisations cannot confidently identify which APIs exist or which ones exchange sensitive data. Without that baseline, policy enforcement, exception handling, and risk prioritisation all rest on partial knowledge. Practitioners should treat discovery as a governance prerequisite, not a periodic audit exercise.

API governance now sits at the intersection of IAM, application security, and third-party risk. That makes fragmented ownership one of the main reasons API controls fail in practice. Authentication, authorisation, protocol hardening, and partner oversight need a shared operating model if organisations want access decisions to stay consistent across the API estate. Practitioners should align API governance to a single accountable owner, not a series of disconnected teams.

From our research library:

• 71% of organizations use third-party APIs, according to Gartner’s 2024 data.
• Read next: API Key Management Guide

What this signals

API inventory is becoming a governance control, not a documentation task. Organisations that cannot identify which APIs exchange sensitive data will continue to miss exposure paths, because policy cannot be enforced against unknown interfaces. The practical shift is from periodic review to continuous discovery tied to ownership and revocation.

Bearer-token trust is a structural weak point in modern API estates. When possession alone authorises access, stolen or intercepted tokens can operate across the trust boundary with little resistance. Security teams should assume that any high-value API path still relying on bearer semantics deserves immediate control redesign.

Third-party access needs the same lifecycle discipline as internal access. Partner integrations frequently survive beyond the original business need, which leaves dormant access paths in place. That is where API security turns into identity governance: not just who can connect, but who still should.

For practitioners

• Define API ownership and revocation paths Assign each API an accountable owner, an authoritative inventory record, and a clear process for disabling access when the API or partner relationship changes.
• Replace bearer trust in high-risk flows Where tokens protect sensitive transactions, use sender-constrained or certificate-bound controls so token possession alone is not enough to gain access.
• Inventory third-party API access Document every external integration, the data it can reach, and the identity or credential type it uses so partner access can be reviewed and removed on schedule.
• Tie discovery to policy enforcement Use API discovery to reconcile live interfaces with approved policy, then investigate any unmanaged endpoint that can exchange sensitive data or invoke privileged functions.
• Review business-logic exposure paths Test APIs for actions that can be replayed, chained, or manipulated in ways the business did not intend, especially where automation or partner access is involved.

Key takeaways

• API vulnerabilities are increasingly governed as identity failures because access, token trust, and partner connections determine the real risk surface.
• The article ties the problem to scale as well as control gaps, citing 84% incident experience, 92% breach prevalence, and up to $87 billion in annual losses.
• Practitioners need a single inventory, stronger token binding, and explicit third-party revocation paths to keep API access governable.

Key terms

• Bearer Token: A bearer token is a credential that grants access to whoever possesses it, without requiring strong proof that the holder is the intended client. In NHI environments, that makes theft and replay the main risk, especially when tokens are long-lived, broadly scoped, or stored in local files.
• Sender-constrained token: A sender-constrained token is tied to a specific client or cryptographic proof, rather than being usable by anyone who steals it. This reduces replay risk and is especially important where tokens can reach automation, services, or agents with broad API access.
• API Inventory: An API inventory is the authoritative record of what interfaces exist, who owns them, what data they touch, and how they are authenticated. For identity governance, it is the baseline control that makes review, monitoring, offboarding, and risk prioritisation possible across distributed services.
• Third-Party API Access: Third-party API access is delegated connectivity granted to external vendors, partners, or service providers. It needs lifecycle governance because the access path often persists beyond the business relationship, creating residual exposure if revocation and review are not enforced.

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