Who is accountable for enforcing supply chain security across repositories and teams?

Why This Matters for Security Teams

Supply chain security across repositories is not just a tooling issue. It is a governance problem that determines who can approve dependencies, who can override controls, and who answers when a compromised package or build pipeline reaches production. The practical question is whether policy is applied consistently across engineering, platform, and security functions, or left to local discretion. That is why control ownership must be explicit, auditable, and tied to risk acceptance rather than informal team habit. Guidance from NIST SP 800-53 Rev 5 Security and Privacy Controls is useful here because it treats accountability, change control, and access enforcement as organisational responsibilities, not developer preferences.

When this is not clearly assigned, exceptions accumulate in pull requests, dependency updates are approved inconsistently, and security findings are rationalised as local tradeoffs. That creates uneven enforcement across repositories, which is exactly where attackers look for the weakest path into software delivery. In practice, many security teams encounter supply chain failures only after a tampered dependency, leaked token, or unreviewed workflow change has already moved through a trusted pipeline, rather than through intentional governance.

How It Works in Practice

Accountability should be defined at three levels: enterprise policy, team implementation, and repository enforcement. Security leadership sets the minimum controls, engineering leadership ensures they are built into delivery workflows, and repository owners apply the controls in a way that is measurable and repeatable. This includes dependency approval rules, branch protection, signed commits where appropriate, token hygiene, build provenance, and exception handling. The point is not to centralise every decision, but to centralise the standard that every team must meet.

In mature environments, the control model usually includes:

• Named control owners for dependency risk, CI/CD permissions, and secret handling.
• Mandatory review for high-risk changes, with documented exceptions and expiry dates.
• Separation of duties between code authors, approvers, and release operators.
• Repository-level baselines that are inherited from centrally managed policy.
• Audit logs that show who approved, changed, or waived a security control.

This becomes especially important when repositories are distributed across business units or when open source dependencies are managed by different teams with different release cadences. The security team should define the control intent, while engineering should operationalise it in pipelines, source control, and artifact management. For identity-linked controls, the same principle applies to non-human identities such as automation accounts, tokens, and service credentials; the OWASP Non-Human Identity Top 10 is a useful reference for understanding why these identities need ownership, rotation, and lifecycle controls. These controls tend to break down when monorepos, inherited workflows, and unmanaged service accounts create overlapping approval paths because no single team can see the full trust chain.

Common Variations and Edge Cases

Tighter supply chain control often increases delivery overhead, requiring organisations to balance release speed against assurance. That tradeoff is real, especially in high-change engineering environments where teams want autonomy but still need uniform control coverage. The right answer is not identical for every repository: low-risk internal projects may accept lighter review, while production systems, regulated workloads, and externally distributed software need stricter enforcement.

Current guidance suggests that there is no universal standard for how much centralisation is enough. Some organisations place accountability in a platform security function, while others assign it to product engineering with security providing policy and assurance. The important distinction is that accountability must be unambiguous even when execution is federated. This becomes even more important where non-human identities are used to automate builds, scans, or deployments, because those identities can silently bypass human review if ownership is unclear. For broader control mapping, the same governance pattern aligns with NIST controls for access, auditability, and configuration management.

Exceptions also arise when third-party vendors or subsidiary teams manage their own repositories. In those cases, security leadership still remains accountable for defining the minimum bar, verifying compliance, and escalating unresolved gaps. Shared ownership is acceptable only when responsibilities are written down, monitored, and tested through audit or incident review.

Related resources from NHI Mgmt Group

• How should teams implement software supply chain security across build pipelines?
• How should security teams reduce the risk of secret theft from npm supply chain attacks?
• What should security teams monitor to detect SaaS supply chain abuse?
• How should security teams manage third-party non-human identities in supply chain environments?