{"id":"CVE-2026-50565","aliases":["GHSA-8wcj-mfrc-jx5q","GO-2026-5850"],"url":"https://o3.security/vulnerability/CVE-2026-50565","summary":"Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container","details":"### Summary\n\nFission builder pods were created with `ServiceAccountName: fission-builder` and no `AutomountServiceAccountToken: false`, so the kubelet auto-mounted the service-account token into every container in the pod — including the\nuser-supplied builder image.\n\n### Details\n\nThe user controls the builder container image, command, and podspec through `Environment.spec.builder.image` / `.container` / `.podspec`. With the SA token auto-mounted at `/var/run/secrets/kubernetes.io/serviceaccount/token` inside that\n container, any code running there inherited the `fission-builder` identity. The `fission-builder` SA holds namespace-wide `get` on `secrets` and `configmaps` (`pkg/utils/serviceaccount.go`), so the user-controlled builder container\ncould read every Secret in the builder namespace by name.\n\nThis is the buildermgr sibling of GHSA-85g2-pmrx-r49q (CVE-2026-46617), whose fix suppressed the SA-token automount on function runtime pods but did not cover the structurally identical primitive in `pkg/buildermgr/envwatcher.go`.\n\n### Impact\n\nA subject with `create`/`update` on `Environment` CRDs in a namespace observed by the buildermgr could read every Secret and ConfigMap in the builder namespace via the auto-mounted `fission-builder` token.\n\n### Fix\n\nFixed in [#3390](https://github.com/fission/fission/pull/3390) and released in [v1.24.0](https://github.com/fission/fission/releases/tag/v1.24.0). In `createBuilderDeployment`:\n\n- Set pod-level `AutomountServiceAccountToken=false` on the initial PodSpec and add the projected fetcher SA-token volume.\n- Re-clamp `AutomountServiceAccountToken=false` after every `MergePodSpec` call so a user-supplied podspec cannot restore the kubelet automount.\n- Mount the token via a projected volume on the fetcher sidecar only, so the legitimate build → archive-upload flow keeps its cluster API access.\n\nReuses the projected-volume helpers from `pkg/executor/util/satoken.go` introduced by the GHSA-85g2-pmrx-r49q fix.\n\n### Behavioural change\n\nThe user-supplied builder container no longer receives an auto-mounted SA token. The fetcher sidecar still gets its token via a projected volume.","published":"2026-06-10T17:28:27.457Z","modified":"2026-10-21T02:52:41.360817440Z","cvss":{"score":4.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.00256,"percentile":0.17349,"asOf":"2026-09-16"},"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-2026-50565.json"},{"type":"ADVISORY","url":"https://github.com/fission/fission/security/advisories/GHSA-8wcj-mfrc-jx5q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50565"},{"type":"FIX","url":"https://github.com/fission/fission/pull/3390"},{"type":"WEB","url":"https://github.com/fission/fission/commit/8fa799417c77ce8a0189d9858bfe11ece29b84a6"},{"type":"PACKAGE","url":"https://github.com/fission/fission"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:52:41.360817440Z"}}