Go · github.com/fission/fission
Fission: Environment Runtime.Container and Builder.Container SecurityContext bypass allows privileged pod creation
A follow-up bypass of the round-4 PodSpec hardening (GHSA-gx55-f84r-v3r7, GHSA-wmgg-3p4h-48x7, GHSA-v455-mv2v-5g92). Those advisories validate and sanitize the PodSpec (spec.runtime.podSpec / spec.builder.podSpec /
function.spec.podSpec), but the Environment CRD also exposes spec.runtime.container and spec.builder.container — a standalone Container merged into the runtime/builder pod whose SecurityContext bypassed both layers.
Admission-layer gap. Environment.Validate() calls ValidatePodSpecSafety() on Runtime.PodSpec and Builder.PodSpec only. That function takes a *PodSpec, so it never inspects the standalone Runtime.Container.SecurityContext
or Builder.Container.SecurityContext.
Merge-layer gap. sanitizeContainerSecurityContext() ran only inside MergePodSpec(). The container field is merged via MergeContainer(), which did not sanitize. With only Runtime.Container set and Runtime.PodSpec nil,
MergePodSpec is never invoked, so the sanitizer never ran.
Affected merge sites: poolmgr (gp_deployment.go), newdeploy (newdeploy.go), and buildermgr (envwatcher.go).
apiVersion: fission.io/v1
kind: Environment
metadata:
name: priv-escape-test
namespace: default
spec:
version: 3
runtime:
image: "ghcr.io/fission/python-env:latest"
container:
name: priv-escape-test
securityContext:
privileged: true
poolsize: 1
The admission webhook accepts this Environment and the resulting pool pod runs with privileged: true. Equivalent bypasses: allowPrivilegeEscalation: true, capabilities.add: ["SYS_ADMIN"], capabilities.add: ["NET_ADMIN","SYS_PTRACE"]. The same attack applies to Builder.Container.
A tenant with environments.fission.io create/update RBAC can run privileged / allowPrivilegeEscalation / dangerous-capability containers in the Fission function or builder namespace, scheduled under the executor's high-privilege
service account — enabling container-sandbox escape, host filesystem and network access, and potential node- and cluster-level compromise. Identical blast radius to GHSA-gx55-f84r-v3r7.
Fixed in #3406 and released in v1.24.0.
ValidateContainerSafety in pkg/apis/core/v1/podspec_safety.go applies the per-container SecurityContext denylist (privileged, allowPrivilegeEscalation, dangerous capabilities) to a
standalone container, and is called from Environment.Validate() for Runtime.Container and Builder.Container.sanitizeContainerSecurityContext() is now invoked inside MergeContainer() itself, covering all three executor/builder call sites.pod-security.kubernetes.io/enforce: restricted.e484df84).Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.
Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.