CVE-2026-50566: Fission Environment Runtime.Container And Builder.Container SecurityContext Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m63v-2g9w-2w6v",
  "modified" : "2026-06-30T18:20:39Z",
  "published" : "2026-06-30T18:20:39Z",
  "aliases" : [ "CVE-2026-50566" ],
  "summary" : "Fission: Environment Runtime.Container and Builder.Container SecurityContext bypass allows privileged pod creation",
  "details" : "### Summary\n\nA 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` /\n`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.\n\n### Details\n\n**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`\nor `Builder.Container.SecurityContext`.\n\n**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,\n`MergePodSpec` is never invoked, so the sanitizer never ran.\n\nAffected merge sites: poolmgr (`gp_deployment.go`), newdeploy (`newdeploy.go`), and buildermgr (`envwatcher.go`).\n\n#### Proof of concept\n\n```yaml\napiVersion: fission.io/v1\nkind: Environment\nmetadata:\n  name: priv-escape-test\n  namespace: default\nspec:\n  version: 3\n  runtime:\n    image: \"ghcr.io/fission/python-env:latest\"\n    container:\n      name: priv-escape-test\n      securityContext:\n        privileged: true\n  poolsize: 1\n```\n\nThe admission webhook accepts this Environment and the resulting pool pod runs with `privileged: true`. Equivalent bypasses: `allowPrivilegeEscalation: true`, `capabilities.add: [\"SYS_ADMIN\"]`, `capabilities.add:\n[\"NET_ADMIN\",\"SYS_PTRACE\"]`. The same attack applies to `Builder.Container`.\n\n### Impact\n\nA 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\nservice 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.\n\n### Fix\n\nFixed in [#3406](https://github.com/fission/fission/pull/3406) and released in [v1.24.0](https://github.com/fission/fission/releases/tag/v1.24.0).\n\n- **Admission layer (primary defence):** a new `ValidateContainerSafety` in `pkg/apis/core/v1/podspec_safety.go` applies the per-container SecurityContext denylist (`privileged`, `allowPrivilegeEscalation`, dangerous capabilities) to a\nstandalone container, and is called from `Environment.Validate()` for `Runtime.Container` and `Builder.Container`.\n- **Merge layer (defence in depth):** `sanitizeContainerSecurityContext()` is now invoked inside `MergeContainer()` itself, covering all three executor/builder call sites.\n\n### Workarounds\n\n- Restrict Environment create/update RBAC to trusted administrators.\n- Deploy a Kyverno / OPA Gatekeeper policy rejecting dangerous Container SecurityContext on Environment CRDs.\n- Label the function/builder namespaces with `pod-security.kubernetes.io/enforce: restricted`.\n\n### References\n\n- GHSA-gx55-f84r-v3r7, GHSA-wmgg-3p4h-48x7, GHSA-v455-mv2v-5g92 — the round-4 PodSpec fixes this advisory bypasses ([#3391](https://github.com/fission/fission/pull/3391), `e484df84`).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/fission/fission"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.24.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.23.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/fission/fission/security/advisories/GHSA-m63v-2g9w-2w6v"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-50566"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fission/fission/pull/3406"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fission/fission/commit/695d3e97e3a20463ab7c8c081843e69e65e952e5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/fission/fission"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fission/fission/releases/tag/v1.24.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-250", "CWE-269" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-30T18:20:39Z",
    "nvd_published_at" : "2026-06-10T18:17:13Z"
  }
}