{"id":"CVE-2026-50545","aliases":["GHSA-wmgg-3p4h-48x7","GO-2026-5860"],"url":"https://o3.security/vulnerability/CVE-2026-50545","summary":"Fission Environment CRD PodSpec Injection Leading to Node Escape and Cluster Takeover","details":"### Summary\n\nA stronger framing of the same root cause as GHSA-gx55-f84r-v3r7: the `Environment.spec.runtime.podSpec` / `spec.builder.podSpec` passthrough lacked validation, and `MergePodSpec` propagated dangerous fields into the generated pods.\n\n### Details\n\nThree independent flaws compounded:\n\n1. **Validate gap.** `pkg/apis/core/v1/validation.go::Environment.Validate` checked only container naming conventions, never `hostPID`/`hostIPC`/`hostNetwork`/`hostPath`/`privileged`.\n2. **UPDATE bypass.** The `pkg/webhook/environment.go` kubebuilder marker registered `verbs=create` only. A tenant could `kubectl apply` a clean Environment and then `kubectl patch` in the dangerous fields — the webhook was never called.\n3. **Merge propagation.** `pkg/executor/util/merge.go::MergePodSpec` unconditionally forwarded `HostPID`, `HostIPC`, `HostNetwork`, `Volumes` (including hostPath), `SecurityContext`, and `ServiceAccountName` into the Deployments\ngenerated by poolmgr / newdeploy / buildermgr.\n\nA `kubectl apply` plus a follow-up `kubectl patch` caused poolmgr to schedule a privileged pod with a host-root mount within roughly 20 seconds. From that pod the cluster CA private key was readable, allowing the attacker to sign\narbitrary kubelet certificates and achieve full cluster takeover.\n\n### Impact\n\n`environments.fission.io` create/update RBAC is escalated to node escape and, via the readable cluster CA key, full cluster takeover.\n\n### Fix\n\nFixed in [#3391](https://github.com/fission/fission/pull/3391) (with the companion buildermgr SA-token fix in [#3390](https://github.com/fission/fission/pull/3390)) and released in\n[v1.24.0](https://github.com/fission/fission/releases/tag/v1.24.0). Each enumerated flaw is addressed:\n\n1. **Validate** — `ValidatePodSpecSafety` is called from `Environment.Validate` for both `Runtime.PodSpec` and `Builder.PodSpec`.\n2. **UPDATE bypass** — the webhook marker is extended to `verbs=create;update`; chart and envtest manifests are aligned.\n3. **Merge propagation** — host namespaces, `ServiceAccountName`, and hostPath volumes are stripped at the merge layer; per-container `privileged`/`allowPrivilegeEscalation` and dangerous capabilities are sanitized.\n\nSee GHSA-gx55-f84r-v3r7 for the detailed fix — both advisories close to the same commit.\n\n### Duplicate handling\n\nThis advisory and GHSA-gx55-f84r-v3r7 were reported separately but close to the same code fix. Both are published to acknowledge each reporter's contribution and to keep the public CVE record clear about the multi-layer nature of the\nissue.","published":"2026-06-10T17:26:20.647Z","modified":"2026-08-12T03:51:13.957471311Z","cvss":{"score":9.9,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"},"epss":{"score":0.003,"percentile":0.22715,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/fission/fission","fixedVersion":"1.24.0"}],"fix":{"url":"https://github.com/fission/fission/pull/3390","label":"fission/fission#3390"},"references":[{"type":"WEB","url":"https://github.com/fission/fission/releases/tag/v1.24.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50545.json"},{"type":"ADVISORY","url":"https://github.com/fission/fission/security/advisories/GHSA-wmgg-3p4h-48x7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50545"},{"type":"FIX","url":"https://github.com/fission/fission/pull/3390"},{"type":"FIX","url":"https://github.com/fission/fission/pull/3391"},{"type":"WEB","url":"https://github.com/fission/fission/commit/8fa799417c77ce8a0189d9858bfe11ece29b84a6"},{"type":"WEB","url":"https://github.com/fission/fission/commit/e484df8460bb4e8026e24210120602aa7f181f64"},{"type":"PACKAGE","url":"https://github.com/fission/fission"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:13.957471311Z"}}