Prevent public access to Google Artifact Registry repositories by using organisation and repository IAM policies that deny anonymous or broad external access. Grant read or write only to the identities that need it, then review inherited permissions and repository defaults. Periodically verify that no artefacts, tags, or service accounts expose build outputs outside the intended trust boundary.
Why repository access controls are the right lever
Google Artifact Registry exposure is usually an IAM problem, not a storage-only problem. Public access appears when a repository, project, or inherited policy grants broad read permissions that were never meant to leave the trust boundary. The practical test is simple: if an unauthenticated user can pull an image or package, the repository is public regardless of how it was intended to be used.
Start by checking the repository-level policy and the parent organisation or project policy together, because inheritance can make a repository public even when its local configuration looks tight. Use the same review to confirm whether the repository is intentionally readable by a wider build or deployment population, or whether anonymous access has slipped in through an inherited binding.
For container and artifact repositories, treat this as part of broader container security: the repository is part of the software supply path, so public read access can expose images, metadata, tags, and the clues attackers use to find embedded secrets or identify internal build patterns.
How to lock down access without breaking builds
The cleanest fix is to remove broad access and replace it with explicit, least-privilege IAM bindings for the identities that actually need the repository. That usually means granting read access only to the build, deployment, or runtime principals that must pull artefacts, and granting write access only to the small set of trusted publish paths.
Do not rely on repository defaults alone. Review whether new repositories inherit permissive project settings, and verify that groups, service accounts, or external collaborators do not have access beyond their intended role. If a repository serves multiple environments, split access by environment rather than assuming a single shared policy will stay safe.
If you need a pattern to compare against, SAP Kubernetes secrets exposure 2023 shows how registry credentials can become a supply-chain exposure when they are left reachable outside the intended boundary. The same lesson applies here: a repository is only private if the identities that can reach it are tightly constrained.
What to verify after the policy change
After tightening access, verify the effective permissions rather than assuming the edit worked. Check that anonymous users, broad all-users style access, and inherited external access are gone, then test the repository from a non-authorised account or a clean service identity to confirm that pulls now fail as expected.
Also review the artefacts already published to the repository. If any image, package, tag, or manifest may have been exposed publicly, treat that as a separate exposure review, because access removal stops future disclosure but does not erase what was already published or indexed.
If you want a broader model for hardening registry-adjacent controls, the SLSA framework is useful for thinking about provenance and integrity, while Google Artifact Registry access control remains the immediate mechanism for preventing public reachability.
Risk and Threat Considerations
Public repository access turns a private software distribution point into a reconnaissance source. Attackers can enumerate artefacts, inspect tags, and look for embedded credentials, internal service names, or deployment clues, then reuse that information for supply-chain abuse or follow-on compromise.
Failure mechanism: A permissive IAM binding at the repository, project, or organisation level grants read access to unauthenticated or over-broad principals, and inherited policy makes the exposure easy to miss during routine review.
Impact: Exposed artefacts can reveal internal code, build outputs, package metadata, and sometimes secrets or deployment patterns, which increases the chance of credential theft, lateral movement, and unauthorised distribution of trusted software.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
CIS Controls v8 and NIST SP 800-53 Rev 5 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| CIS Controls v8 | CIS-6 — Access Control Management | Restricting repository access directly maps to controlling who can read or publish artefacts. |
| Recommendation — Enforce least-privilege access and remove broad repository bindings. | ||
| NIST SP 800-53 Rev 5 | AC-3 — Access Enforcement | Repository IAM policies must enforce who can access artefacts and metadata. |
| AC-6 — Least Privilege | Public access prevention depends on limiting identities to the minimum needed rights. | |
| Recommendation — Configure repository policies to deny unauthorised reads and writes. Grant repository access only to the identities that need it. | ||
| ISO/IEC 27001:2022 | A.5.15 — Access control | The question is about controlling access to a cloud repository and preventing public reachability. |
| Recommendation — Apply access control rules that block anonymous and overly broad repository access. | ||
Practitioner Guidance
What to verify: Confirm the effective policy at every layer, not just the repository object, and test access from a non-privileged identity after the change. If the repository still allows unauthenticated pulls, the fix is incomplete.
Decision rule: If any artefact in the repository is intended only for internal deployment, treat public-read access as a defect, not a convenience setting. If external access is truly required, scope it to a dedicated repository or a tightly controlled identity set rather than broad anonymous exposure.
Practitioner takeaway: The control is not merely "make the repository private", it is to make the effective access path explicit, reviewable, and narrow enough that inherited permissions cannot reopen the boundary later.
Related resources from NHI Mgmt Group
- How do you enforce public access prevention on Google Cloud Storage buckets?
- How do you prevent anonymous public access to Azure Blob Storage containers?
- How do you prevent public access through Amazon SNS and SQS resource policies?
- How do you prevent public access to AWS Lambda functions and function URLs?
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Reviewed and updated by the NHIMG editorial team on October 20, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org