{"id":"CVE-2026-49823","title":"Fission: Cross-namespace Package read via unvalidated PackageRef in Function admission webhook","summary":"Fission: Cross-namespace Package read via unvalidated PackageRef in Function admission webhook","severity":"high","cvss":7.7,"cwe":["CWE-284","CWE-863"],"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-3r8v-2xmj-5c39","references":[{"url":"https://github.com/fission/fission/security/advisories/GHSA-3r8v-2xmj-5c39"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49823"},{"url":"https://github.com/fission/fission/pull/3389"},{"url":"https://github.com/fission/fission/commit/80e7ba55228e1ef426f51353e25d2682ec61de34"},{"url":"https://github.com/fission/fission/releases/tag/v1.24.0"},{"url":"https://github.com/advisories/GHSA-3r8v-2xmj-5c39"}],"tags":["ghsa","go"],"epss":0.00265,"epssPercentile":0.18694,"ingestedAt":"2026-06-30T21:24:14.412Z","slug":"CVE-2026-49823","body":"## Overview\n\n### Summary\n\nA Fission Function spec carries three reference types — Secret, ConfigMap, and Package. The first two were namespace-validated by the admission webhook; `PackageRef.Namespace` was not.\n\n### Details\n\nA tenant with `functions.fission.io/create` in their own namespace could set `spec.package.packageref.namespace` to any other namespace. When the function is invoked, the fetcher sidecar reads the victim Package using the\n`fission-fetcher` service account's namespace-wide `get packages` permission and writes its contents to `/userfunc/deployarchive` inside the attacker's pool pod, exposing the victim's source code and any embedded credentials.\n\nThe `fission-fetcher` SA holds `get packages` in every configured function namespace (granted by `charts/fission-all/templates/_function-access-role.tpl`), so the namespace check was the only barrier between the attacker and any\nin-cluster Fission Package.\n\n### Impact\n\nA function author in one namespace could read the deployment archive — and therefore the source code and embedded secrets — of any Package in any other namespace.\n\n### Fix\n\nFixed in [#3389](https://github.com/fission/fission/pull/3389) and released in [v1.24.0](https://github.com/fission/fission/releases/tag/v1.24.0).\n\nThe admission webhook (`pkg/webhook/function.go::Validate`) rejects `Function.spec.package.packageref.namespace != metadata.namespace`. An empty namespace remains accepted (controllers default it to the function's namespace). This\nshipped together with the EnvironmentRef cross-namespace check (GHSA-cvw6-gfvv-953q).\n\n### Behavioural change\n\nFunctions that explicitly set `spec.package.packageref.namespace` to a different namespace are now rejected at admission.\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":"twilight","depthScore":42,"depthScoreParts":{"impact":42.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}