CVE-2026-49821: Fission Cross-namespace Environment Reference Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vjhc-cf4p-72q4",
  "modified" : "2026-06-30T18:15:27Z",
  "published" : "2026-06-30T18:15:27Z",
  "aliases" : [ "CVE-2026-49821" ],
  "summary" : "Fission: Cross-namespace Environment reference in Package allows build-time command execution and SA token exfiltration",
  "details" : "### Summary\n\nFission's `buildermgr` controller processed `Package` CRDs without verifying that `Package.spec.environment.namespace` matched `Package.metadata.namespace`.\n\n### Details\n\nAn attacker with `packages.fission.io/create` in their own namespace could set `spec.environment.namespace` to any other tenant's namespace. The controller then used its high-privilege service account to fetch the Environment\ncross-namespace and dispatch the build command into the **victim namespace's** builder pod.\n\nThe build command's stdout is written verbatim into `Package.status.buildlog`. By running malicious code through an npm `preinstall` lifecycle hook (or any equivalent build step), the attacker could read the victim namespace's\n`fission-builder` Bearer token from inside that builder pod and surface it through the build log — then use the leaked token to read every Secret and ConfigMap in the victim namespace.\n\n### Impact\n\nCross-tenant compromise: a package author in one namespace could execute code inside another tenant's builder pod and exfiltrate that namespace's `fission-builder` service-account token, giving namespace-wide secret and configmap read in\n the victim namespace.\n\n### Fix\n\nFixed in [#3379](https://github.com/fission/fission/pull/3379) and released in [v1.24.0](https://github.com/fission/fission/releases/tag/v1.24.0). Two checks in series:\n\n- **Admission webhook** (`pkg/webhook/package.go::Validate`) rejects `Package.spec.environment.namespace != Package.metadata.namespace`. An empty namespace is still accepted; the controllers default it to the package's own namespace.\n- **Controller belt-and-braces:** the same check is repeated in `pkg/buildermgr/pkgwatcher.go::build` and `pkg/buildermgr/common.go::buildPackage` before the cross-namespace `Environments(...).Get` call, so a stale Package CR or a\nwebhook-bypass cluster (`failurePolicy=Ignore`) cannot exploit the primitive either.\n\n### Behavioural change\n\nPackages that explicitly set `spec.environment.namespace` to a different namespace are now rejected at admission. Empty-string remains accepted (resolves to the package's own namespace, the same as the prior implicit behaviour).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"
  } ],
  "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-vjhc-cf4p-72q4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-49821"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fission/fission/pull/3379"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/fission/fission/commit/e2b92663499f4dc3a1e2d38178f39c3c65e0134a"
  }, {
    "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-441", "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-30T18:15:27Z",
    "nvd_published_at" : "2026-06-10T18:17:10Z"
  }
}