Why do package publish tokens create supply chain risk when reused in CI pipelines?

Why reuse turns a publish token into supply chain authority

Package publish tokens are not just login secrets. In practice, they often carry the ability to create, overwrite, or promote releases, which means whoever holds them can influence what downstream consumers install. When that token is reused inside CI, the pipeline inherits release authority even when its inputs are not fully trusted.

The core problem is scope mismatch. A token that is acceptable in a tightly controlled release workstation becomes dangerous when exposed to build steps, test fixtures, pull requests, dependency installation, or other pipeline paths that may process attacker-controlled content. That is why a leaked or reused publish token can become a package integrity issue, not merely an account issue.

Publishing and release automation are only safe when the credential’s permissions match the exact action being performed. If the same token can both read trusted inputs and publish new artifacts, the pipeline can cross the trust boundary without a human review step. The result is a shortcut from untrusted code execution to registry mutation.

How CI exposure changes the attack path

CI systems amplify token risk because they are designed to automate. They often run with broad environment access, cache artifacts, call external services, and execute scripts from dependencies or test harnesses. If a publish token is reachable anywhere in that environment, an attacker may not need to steal it directly, they only need a path to read environment variables, job logs, workspace files, or injected process state.

That changes the attack from “steal a secret” to “steer a pipeline.” A malicious pull request, compromised dependency, or poisoned build step can wait for the job to expose the token, then publish a modified version, retag an existing release, or insert a payload that is later trusted by consumers. The harm is broader because registry publication is a distribution event.

This is why package publishing belongs in the same mental model as build provenance and release integrity. SLSA is useful here because it treats the build and release path as something that must be attributable and constrained, not assumed safe just because it is automated.

What good containment looks like for release credentials

The safest pattern is to separate build identity from publish authority. CI jobs that compile, test, or package artifacts should not also hold the standing right to publish to a public registry. Instead, release authority should be short-lived, tightly scoped, and issued only at the final release step, after the artifact has been verified.

That usually means three practical controls: limit the token to one registry and one package, bind it to the smallest possible workflow surface, and make the publish action dependent on a trusted release event rather than a general build job. If the token can be reused across branches, environments, or repositories, it is already wider than the task it is supposed to support.

Release engineering teams should also treat publish tokens as part of supply chain governance, not as ordinary CI secrets. NIST SSDF (SP 800-218) is a strong fit for this control pattern because it pushes teams to protect software integrity through controlled build and release practices, while OpenSSF is useful for broader supply chain guidance and hardening practices.

Practitioner Guidance

What to prioritise: Treat any publish token that can be reached by CI as a release-critical secret. If the token is long-lived or reusable across jobs, assume the blast radius includes every package version the pipeline can mutate.

What to verify: Confirm that the publish step is isolated from test and build steps, that the token is scoped to the minimal registry and package, and that untrusted pull request contexts cannot access the credential or the environment that contains it.

Common mistake: Teams often assume a “private” CI secret is safe because it is not committed to source control. The real question is whether the pipeline context itself is trustworthy enough to hold publish authority.

Practitioner takeaway: Reuse is what converts a publish token from a release credential into a supply chain control point, so the right design is to make publishing the narrowest, least reusable, most observable step in the pipeline.

Related resources from NHI Mgmt Group

• Why do CI and package-maintainer secrets create outsized supply chain risk?
• Why do package-manager bypasses increase supply-chain risk for CI/CD pipelines?
• Why do standing CI/CD tokens create so much risk in supply chain attacks?
• Why do compromised CI pipelines create such broad supply chain risk?