Fission, a Kubernetes-native serverless framework, allowed a tenant with environments.fission.io create/update RBAC to specify privileged containers—including setting allowPrivilegeEscalation and dangerous capabilities—in functions or builders. The executor’s high‑privilege service account would then launch these containers, bypassing the typical container sandbox. The result is a container‑sandbox escape that can grant access to the node’s filesystem, network, and potentially the entire cluster, enabling a full compromise of the infrastructure.

Any installation of Fission prior to version 1.24.0 that permits tenants to create or update environments. Attacks apply to the function and builder namespaces where privileged containers may be run; the issue is not limited to a single host or user.

The CVSS score of 9.9 marks this as a critical vulnerability. The EPSS score is not available, so the current likelihood of exploitation is unclear, but the severity of the impact is high. It is not listed in CISA KEV, indicating no public exploit has been documented yet. An attacker would likely need to orchestrate privileged container creation through the tenant’s RBAC permissions, a step that requires prior access or compromise of tenant privileges. Once achieved, the attacker can escape the sandbox and gain host‑level or cluster‑level control.