Spinnaker’s Kustomize bake operation processes yaml manifests for the rosco component without properly handling unsafe YAML tags, a flaw identified as CWE‑502. When a bake is performed, an attacker can supply a crafted yaml file that is deserialized by rosco, allowing arbitrary code to be executed inside the rosco pod. The impact is the ability to run code within the container that runs the rosco deployment, potentially leading to further compromise of the infrastructure that uses the affected Spinnaker instance.

All Spinnaker deployments that include a rosco component before the following releases are affected: the 2026 release line before 2026.1.1, the 2026.0 line before 2026.0.3, the 2025.4 line before 2025.4.4, and the 2025.3 line before 2025.3.4. These versions expose the rosco pods to remote code execution if a Kustomize bake is triggered.

The vulnerability carries a CVSS score of 7.5, indicating medium‑high severity. Its EPSS score is below 1%, suggesting a low probability of active exploitation at the present time, and it is not listed in CISA’s KEV catalog. Based on the description, it is inferred that the attacker must be able to initiate a Kustomize bake against the rosco instance—typically via the CI/CD pipeline or a privileged user with access to the bake operation—to inject malicious yaml.