Why do access reviews often fail when reviewer resolution is not tightly governed?

Why This Matters for Security Teams

Reviewer resolution is not a clerical detail. In access reviews, the named reviewer determines whether privileged access is validated, rejected, or left untouched. When ownership is ambiguous, review workflows drift into queue management instead of governance, and exceptions accumulate without accountability. That undermines least privilege, auditability, and the credibility of the entire certification program.

This is especially risky for non-human identities, service accounts, and shared credentials because no human user is guaranteed to “notice” drift. The control expectation is clearer in the NIST Cybersecurity Framework 2.0 and in the OWASP Non-Human Identity Top 10: identities must have accountable ownership, not just an assigned ticket. NHIMG’s Ultimate Guide to NHIs and 52 NHI Breaches Analysis both show how weak lifecycle handling turns ownership gaps into exposed access paths.

In practice, many security teams only discover the problem after an overdue certification, a self-review, or a failed audit trace has already allowed risky access to persist.

How It Works in Practice

A reliable review process needs a governed resolution chain before the review starts. That means each record has a primary reviewer, a documented fallback, and an explicit final owner of record if neither responds. The process should also define what happens when the reviewer and approver are the same person, when a manager changes, or when a business owner leaves the organisation. Without those rules, access certification becomes a routing problem instead of an access control decision.

Operationally, teams usually tighten this with three layers:

• Owner mapping that ties every account, role, or entitlement to a responsible business or service owner.
• Escalation logic that reassigns stalled items after a fixed SLA, rather than letting them age indefinitely.
• Exception handling that forces explicit closure for self-reviews, orphaned accounts, and disputed access.

For NHIs, that means the owner cannot be inferred from a person’s title alone. The record must point to the workload, application, or automation pipeline that actually depends on the identity. NHIMG’s Lifecycle Processes for Managing NHIs is useful here because it frames ownership as part of lifecycle control, not a one-time onboarding task. Where implementations mature, reviewer resolution is coupled to authoritative identity data, not manually curated spreadsheets. That is consistent with NIST SP 800-53 Rev 5 Security and Privacy Controls, which expects accountable review and least-privilege enforcement through defined control ownership.

These controls tend to break down when identity sources are fragmented across multiple systems, because the workflow cannot reliably determine who should decide, who should backstop, and who ultimately owns the risk.

Common Variations and Edge Cases

Tighter reviewer governance often increases operational overhead, requiring organisations to balance fast completion against stronger accountability. That tradeoff is real, especially in large environments where managers change frequently or service ownership is split across platform, product, and security teams.

Current guidance suggests a few practical exceptions should be handled explicitly rather than informally. Temporary proxies can approve on behalf of an unavailable owner, but only if delegation is time-bound and logged. Shared services should use a named control owner, not a team mailbox. Self-reviews are best treated as a policy violation unless a separate independent approver exists. For service accounts and automation, the review target should be the workload owner, not the engineer who created the account months earlier.

NHIMG’s Top 10 NHI Issues highlights why this matters in environments with high identity churn: when ownership is stale, remediation becomes performative instead of effective. The right pattern is to keep the review decision simple, but the ownership graph precise. If the organisation cannot answer who is responsible when the primary reviewer is unavailable, the process is already failing. In mixed human and machine estates, that failure shows up fastest in orphaned service accounts and long-lived credentials, where no one has a natural incentive to act.

Related resources from NHI Mgmt Group

• How should security teams run access reviews for non-human identities?
• When do NHI access reviews create more value than a one-time cleanup?
• Why do access reviews often fail in large organisations?
• Why do access reviews often fail to reduce audit findings?