CVE-2026-59891 is a critical-severity (CVSS 9.6) CWE-522 vulnerability in @sigstore/oci. A fix is available for @sigstore/oci — see the affected versions and patch details below.
Credential confusion in @sigstore/oci can leak registry credentials to an attacker-controlled registry
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-59891.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-59891 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 390,807 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@sigstore/ocinpmDescription
Impact
This is a credential-exposure / credential-confusion issue.
getRegistryCredentials() reads credentials from the Docker config file (~/.docker/config.json) and selects an entry by checking whether any configured auth key contains the target registry string:
Object.keys(dockerConfig.auths || {}).find((key) => key.includes(registry))
Because this is a substring match rather than an exact host match, credentials configured for one registry can be selected for — and transmitted to — a different registry whose hostname has a substring relationship with a configured auth key (for example, an attacker-controlled cr.io matches a configured ghcr.io).
Who is impacted: Any consumer of @sigstore/oci that uploads artifacts to an OCI registry using credentials from a Docker config, where the destination registry/image reference can be influenced by an untrusted party. This includes @actions/attest and the actions/attest, actions/attest-build-provenance, and actions/attest-sbom GitHub Actions when run with push-to-registry: true, where the subject-name input determines the destination registry.
This is classified as a critical vulnerability given the potential, in a theoretical worst-case scenario, to expose long-lived registry credentials. However, in practice, exploitation requires all of the following:
- The Docker config on the host contains credentials for a registry.
- The destination registry/image reference is influenced by an untrusted source.
- The attacker controls a registry whose hostname is a substring of (or is otherwise contained within) a configured Docker auth key.
Under those conditions, registry credentials present on the host (e.g. a GHCR, Docker Hub, or cloud-registry token) can be sent to an attacker-controlled registry during the authentication exchange.
Patches
Fixed in @sigstore/[email protected]. Credential selection now requires an exact host match: both the target registry and each Docker auth key are canonicalized — stripping any https?:// scheme and path and normalizing the Docker Hub aliases (index.docker.io / registry-1.docker.io / docker.io) — and compared for equality. When no exact match exists, credential lookup now fails rather than falling back to an unrelated credential.
- Affected versions:
<= 0.7.0(all releases from0.1.0). - Patched version:
0.7.1.
Downstream consumers should pick up the patched @sigstore/oci; subsequent releases of @actions/attest and the actions/attest* GitHub Actions will bundle the fix.
Workarounds
- Treat the destination registry/image reference as trusted input — do not allow untrusted sources to influence the registry/image reference passed to
@sigstore/oci(or thesubject-nameofactions/attest*whenpush-to-registry: true). - Limit the credentials available in the host's Docker config to only those required for the operation, and avoid authenticating to registries whose hostnames have substring relationships with potential untrusted destinations.
- Scope registry tokens narrowly and prefer short-lived credentials.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @sigstore/oci | all versions | 0.7.1npm install @sigstore/oci@0.7.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sigstore/oci, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @sigstore/oci to 0.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59891 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-59891 in your dependencies?
Find it across npm, including transitive dependencies.