{"id":"CVE-2026-50565","title":"Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container","summary":"Fission builder pods auto-mount the fission-builder ServiceAccount token in the user-supplied builder container","severity":"medium","cvss":4.9,"cwe":["CWE-250","CWE-269","CWE-538"],"vendor":"fission","product":"github.com/fission/fission","ecosystem":"go","affected":["github.com/fission/fission <= 1.23.0"],"patched":["github.com/fission/fission 1.24.0"],"published":"2026-06-30","updated":"2026-06-30","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-8wcj-mfrc-jx5q","references":[{"url":"https://github.com/fission/fission/security/advisories/GHSA-8wcj-mfrc-jx5q"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50565"},{"url":"https://github.com/fission/fission/pull/3390"},{"url":"https://github.com/fission/fission/commit/8fa799417c77ce8a0189d9858bfe11ece29b84a6"},{"url":"https://github.com/fission/fission/releases/tag/v1.24.0"},{"url":"https://github.com/advisories/GHSA-8wcj-mfrc-jx5q"}],"tags":["ghsa","go"],"epss":0.00256,"epssPercentile":0.17469,"ingestedAt":"2026-06-30T21:24:14.405Z","slug":"CVE-2026-50565","body":"## Overview\n\n### 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.\n\n## Affected packages\n\n- `github.com/fission/fission <= 1.23.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/fission/fission 1.24.0`","depth":"sunlit","depthScore":27,"depthScoreParts":{"impact":27,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}