Third-party relationships can create unexpected security gaps if access is granted without the same verification applied to internal users and systems. Vendor sprawl also increases operating cost and expands the number of trust decisions security teams must manage. Zero Trust extends the same discipline to external parties, so every connected relationship must be evaluated and monitored.
How Third-Party Inclusion Changes Zero Trust Governance
Zero Trust is supposed to remove implicit trust, so third parties immediately raise the bar for governance. A vendor connection is not just another account or integration, it is an external trust decision that must be justified, scoped, and continuously revalidated. The practical change is that vendor access cannot be treated as a procurement checkbox or one-time onboarding event. It becomes part of the same Zero Trust Architecture discipline that governs internal access paths.
That shift matters because vendors often arrive through different business owners, different technical controls, and different offboarding habits. If those relationships are not normalised into a shared governance model, the organisation ends up with inconsistent approval standards, uneven monitoring, and unclear accountability for what each vendor can reach. The result is not only more exposure, but also more ambiguity about who is responsible when access outlives the business need.
For teams managing identity-heavy environments, the issue is not abstract. Third-party access often depends on credentials, tokens, service accounts, or delegated access paths that can be reused, over-scoped, or forgotten. NHI governance becomes material because external relationships can multiply the number of non-human access points security teams must inventory and control. NHIMG’s Ultimate Guide to NHIs is a useful reference for the lifecycle, visibility, and rotation problems that emerge when those trust relationships scale.
Where Risk Accumulates: Scope, Visibility, and Vendor Sprawl
Once third parties are admitted into Zero Trust governance without proper checks, the main failure is not usually a single dramatic breach, it is accumulated exposure. Small exceptions add up: one vendor gets broader access than intended, another keeps stale credentials, and a third receives access to systems that were never part of the original business case. Over time, the trust boundary expands faster than the control model that was supposed to contain it.
Visibility tends to degrade at the same time. Security teams may know a vendor exists, but not which accounts, secrets, APIs, or environments that vendor can actually touch. That is why dormant or under-reviewed access becomes dangerous, especially when vendor relationships outlive the project that justified them. NHIMG research notes that only 5.7% of organisations have full visibility into their service accounts, and that gap is exactly the kind of blind spot vendor sprawl exploits.
Third-party exposure also changes the risk equation for the whole program. NHIMG’s The 2026 Infrastructure Identity Survey reports that 90% of IT leaders say properly managing NHIs is essential for a successful zero-trust implementation, which aligns with the practical reality that external trust is only safe when the connected identity, privilege, and lifecycle are visible enough to govern.
What Good Governance Requires Before a Vendor Connects
The right control point is before access is granted, not after something goes wrong. Proper risk checks should confirm the vendor’s business need, the exact systems in scope, the minimum access required, the credential type being used, and the monitoring that will prove the access stays bounded. If any of those elements is vague, the vendor relationship is too loose for Zero Trust governance.
Failure mechanism: The organisation treats vendor onboarding as a static approval rather than a continuously governed access decision, so inherited trust, stale permissions, and opaque integrations persist unnoticed.
Impact: Attack surface grows, revocation becomes slower and less reliable, and a compromise in the vendor environment can translate into direct access to internal systems or data.
Practitioners should pay special attention to third-party secrets and tokens, because those are often the mechanism that turns a relationship into an access path. A useful example is the Salesloft OAuth token breach, which shows how delegated access can become an enterprise exposure if token governance is weak. External trust is safest when access is narrow, revocable, and measured continuously rather than assumed to remain legitimate.
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, NIST Zero Trust (SP 800-207) and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | GV.RM-01 — Risk Management Strategy | Vendor inclusion needs explicit risk acceptance and governance. |
| Recommendation — Document third-party access risks and approve only scoped exceptions. | ||
| NIST Zero Trust (SP 800-207) | AC-1 — Policy Enforcement Point and Policy Decision | Zero Trust depends on continuous policy decisions for external access. |
| Recommendation — Enforce vendor access through policy checks, not static trust. | ||
| CIS Controls v8 | 6.1 — Establish an Access Granting Process | Third-party access must be approved, scoped, and reviewed consistently. |
| Recommendation — Require formal approval and least-privilege scoping for vendor accounts. | ||
| OWASP Non-Human Identity Top 10 | NHI-02 — Secrets and Credential Management | Vendor access often relies on tokens, keys, and other secret material. |
| NHI-05 — Access Governance and Least Privilege | External vendors need tight entitlement scope and periodic review. | |
| NHI-08 — Third-Party and Supply Chain Risk | The question is specifically about third-party vendors inside Zero Trust governance. | |
| Recommendation — Inventory and rotate vendor secrets on a defined schedule. Limit vendor entitlements to the minimum needed and recertify them regularly. Assess vendor trust paths and block access when due diligence is incomplete. | ||
Practitioner Guidance
What to verify: Before a vendor is placed inside Zero Trust governance, verify that the access path is tied to a named business purpose, a specific owner, and a documented offboarding trigger. If you cannot identify all three, the relationship is not ready for production access.
What changes at scale: As vendor count grows, the hard part is not approval volume, it is exception management. Teams need a repeatable way to distinguish low-risk integrations from relationships that expose sensitive systems, broad tokens, or reusable credentials, because those are the cases that drive most of the hidden blast radius.
Practitioner takeaway: Zero Trust only stays trustworthy when third-party access is governed as a living security relationship, not a procurement artifact, so the central question is whether each vendor remains narrowly scoped, observable, and easy to revoke.
Related resources from NHI Mgmt Group
- Why do third-party contractors and vendors create extra risk in zero trust environments?
- What happens when personal data is sent to third party vendors without proper DPDP controls?
- How should security teams implement automated third-party risk mitigation without losing governance control?
- Why do third-party connections increase operational risk in Zero Trust environments?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 17, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
