{"id":"GHSA-gx55-f84r-v3r7","summary":"Fission Environment CRD podspec passthrough enables hostPID/hostNetwork/privileged pods, node escape","details":"### Summary\n\nFission's `Environment` CRD exposes `spec.runtime.podSpec` and `spec.builder.podSpec`, which are merged into the Kubernetes pod specs for runtime and builder pods. The merge logic propagated `hostNetwork`, `hostPID`, `hostIPC`, container\n `privileged`, and `serviceAccountName` from the user-supplied podspec with no filtering, and `Environment.Validate` performed no security-relevant checks on these fields.\n\n### Details\n\nA namespace user with `create`/`update` on `environments.fission.io` could produce privileged, host-network, hostPID pods in the Fission function or builder namespace. Because the Helm chart created the `fission-function` and\n`fission-builder` namespaces with no `pod-security.kubernetes.io/enforce` labels, Kubernetes Pod Security Admission did not catch the escape either.\n\nFrom a host-network privileged pod with hostPID, the attacker could `nsenter` into the host, read cloud-metadata credentials, access the container-runtime socket, pivot to other namespaces, and fully compromise the node.\n\n### Impact\n\n`environments.fission.io` create/update RBAC is escalated to node compromise — host filesystem and network access on the scheduling node, and from there potential cluster-wide takeover.\n\n### Fix\n\nFixed in [#3391](https://github.com/fission/fission/pull/3391) and released in [v1.24.0](https://github.com/fission/fission/releases/tag/v1.24.0). Denylist at admission (the primary defence) plus belt-and-braces at the merge layer.\n\n**Admission denylist** (`pkg/apis/core/v1/podspec_safety.go::ValidatePodSpecSafety`), called from `Environment.Validate` for both `Runtime.PodSpec` and `Builder.PodSpec`:\n\n- pod-level: `HostNetwork`, `HostPID`, `HostIPC`, `ServiceAccountName` / `DeprecatedServiceAccount` override, hostPath volumes;\n- per-container: `SecurityContext.Privileged=true`, `SecurityContext.AllowPrivilegeEscalation=true`, dangerous capabilities (`SYS_ADMIN`, `NET_ADMIN`, `SYS_PTRACE`, `SYS_MODULE`, `DAC_READ_SEARCH`, `DAC_OVERRIDE`).\n\n**Update-bypass closed:** the `Environment` validating-webhook marker is extended from `verbs=create` to `verbs=create;update` (chart and envtest manifests aligned).\n\n**Merge-layer belt-and-braces** (`pkg/executor/util/merge.go`): even if admission is bypassed (`failurePolicy=Ignore` or stale pre-webhook objects), the denylisted pod-level fields are stripped and per-container dangerous settings are\nsanitized before the merge (with `SecurityContext` deep-copied first so cached informer objects are not mutated). Legitimate operator hardening via the chart's pod-level `securityContext` (fsGroup, runAsNonRoot, runAsUser) still flows\nthrough.\n\n### Behavioural change\n\nEnvironments that explicitly set any denylisted field are now rejected at admission. There is no legitimate Fission use case — these primitives exist for cluster operators, not Environment authors.\n\nThis is the same root cause and fix as GHSA-wmgg-3p4h-48x7.","aliases":["CVE-2026-50564","GO-2026-5855"],"modified":"2026-07-07T16:11:33.913554523Z","published":"2026-06-30T18:19:32Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-06-30T18:19:32Z","nvd_published_at":"2026-06-10T18:17:12Z","cwe_ids":["CWE-269","CWE-284","CWE-693"],"severity":"CRITICAL"},"references":[{"type":"WEB","url":"https://github.com/fission/fission/security/advisories/GHSA-gx55-f84r-v3r7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50564"},{"type":"WEB","url":"https://github.com/fission/fission/pull/3391"},{"type":"WEB","url":"https://github.com/fission/fission/commit/e484df8460bb4e8026e24210120602aa7f181f64"},{"type":"PACKAGE","url":"https://github.com/fission/fission"},{"type":"WEB","url":"https://github.com/fission/fission/releases/tag/v1.24.0"}],"affected":[{"package":{"name":"github.com/fission/fission","ecosystem":"Go","purl":"pkg:golang/github.com/fission/fission"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.24.0"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 1.23.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-gx55-f84r-v3r7/GHSA-gx55-f84r-v3r7.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}