Vault coexistence is the state where a new PAM capability must work alongside an existing credential vault rather than replace it. The governance risk is fragmentation, because storage, checkout, rotation, and revocation can become split across tools without a clear source of authority.
Expanded Definition
Vault coexistence describes a transitional operating model in which a new PAM capability must share responsibility with an existing credential vault instead of replacing it outright. In NHI security, this matters because the vault is often not just a repository; it may also control checkout, rotation, approval workflows, and revocation. When two systems split those responsibilities, governance can become ambiguous unless one clearly remains the source of authority.
The term is closely related to migration planning, but it is not the same as simple integration. Coexistence implies parallel control planes, overlapping policy enforcement, and a need to reconcile lifecycle events across tools. Definitions vary across vendors, and no single standard governs this yet, so practitioners should treat vault coexistence as an operational pattern rather than a formal control category. A useful reference point for the broader governance lens is the NIST Cybersecurity Framework 2.0, especially where asset governance and access control depend on consistent authority.
The most common misapplication is assuming that two vaults can operate independently during migration, which occurs when checkout and rotation are split before ownership and approval rules are unified.
Examples and Use Cases
Implementing vault coexistence rigorously often introduces temporary complexity in policy enforcement, requiring organisations to weigh migration speed against the risk of split authority.
- A team keeps an incumbent credential vault for legacy apps while a new PAM platform manages only privileged sessions, with both tools needing synchronized rotation rules.
- An organisation uses the vault for storage but routes checkout approvals through a new access workflow, creating a dependency on clear reconciliation for revocation events.
- During a phased migration, application owners continue to retrieve secrets from the old vault while new workloads are onboarded into a different system, which demands strict inventory mapping. The Guide to the Secret Sprawl Challenge explains why this inventory step is often harder than expected.
- A security team uses a dynamic secret pattern for new services while older static credentials remain in the previous vault, making lifecycle consistency essential; see the Ultimate Guide to NHIs, Static vs Dynamic Secrets for the underlying credential model.
- Offboarding processes must revoke access in both systems until the legacy vault is fully retired, otherwise stale credentials can remain usable after policy changes.
This pattern is most defensible when one platform is explicitly designated as authoritative for rotation and revocation, while the other is constrained to storage or read-only transition support.
Why It Matters in NHI Security
Vault coexistence becomes a governance risk when it is treated as an implementation detail instead of an identity control issue. In NHI environments, credentials are often distributed across CI/CD systems, ticketing tools, and runtime platforms, so any split in authority can amplify secret sprawl, delay revocation, and obscure which vault actually owns the lifecycle of a given secret. NHIMG research found that 62% of all secrets are duplicated and stored in multiple locations, which makes coexistence especially dangerous when organisations cannot confirm the system of record.
The problem is not the temporary presence of two tools. The problem is the absence of explicit ownership for storage, checkout, rotation, and retirement. That is where leaked tokens, duplicated secrets, and stale access tend to survive policy changes. The operational impact aligns with broader security governance concerns described in the 2025 State of NHIs and Secrets in Cybersecurity, and the control mindset should also map to the NIST Cybersecurity Framework 2.0 for access and protection discipline. Organisations typically encounter the consequences only after a secret leak or failed revocation, at which point vault coexistence becomes operationally unavoidable to address.
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-02 | Coexistence can create secret sprawl and unclear custody across tools. |
| NIST CSF 2.0 | PR.AC-1 | Access authority must remain clear when two vault systems operate in parallel. |
| NIST Zero Trust (SP 800-207) | SC | Zero trust requires continuous verification even when credentials traverse multiple control planes. |
Designate one authoritative vault path and reconcile all secret custody, rotation, and revocation flows.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on June 10, 2026.
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