GHSA-96qw-h329-v5rg: Shakapacker Shakapacker Has Environment Variable Leak Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-96qw-h329-v5rg",
  "modified" : "2026-01-08T21:13:37Z",
  "published" : "2026-01-08T21:13:37Z",
  "aliases" : [ ],
  "summary" : "Shakapacker has environment variable leak via EnvironmentPlugin that exposes secrets to client-side bundles",
  "details" : "### Summary\n\nSince 2017, the default webpack plugins have passed the entire `process.env` to `EnvironmentPlugin`. This pattern exposed ALL build environment variables to client-side JavaScript bundles whenever application code (or any dependency) referenced `process.env.VARIABLE_NAME`.\n\nThis is not a regression - the vulnerable code has existed since the original Webpacker implementation. No recent code change in Shakapacker triggered this issue.\n\n### Impact\n\nAny environment variable in the build environment that is referenced in client-side code (including third-party dependencies) is embedded directly into the JavaScript bundle. This includes:\n\n- `DATABASE_URL` - Database credentials\n- `AWS_SECRET_ACCESS_KEY` - AWS credentials  \n- `RAILS_MASTER_KEY` - Rails encrypted credentials key\n- `STRIPE_SECRET_KEY`, `TWILIO_AUTH_TOKEN` - Third-party API keys\n- Any other secrets present in the build environment\n\n**Severity**: Critical - secrets are exposed in publicly accessible JavaScript files.\n\n### Root Cause\n\nThe original code used:\n```javascript\nnew webpack.EnvironmentPlugin(process.env)\n```\n\nThis makes every environment variable available for substitution. If any code references `process.env.SECRET_KEY`, that value is embedded in the bundle.\n\n### Patches\n\nUpgrade to version 9.5.0 or later, which uses an allowlist approach that only exposes `NODE_ENV`, `RAILS_ENV`, and `WEBPACK_SERVE` by default.\n\n### Workarounds\n\nIf developers cannot upgrade immediately:\n1. Audit client-side code and dependencies for any `process.env.X` references to sensitive variables\n2. Remove sensitive variables from the build environment\n3. Override the default plugins with a custom webpack/rspack config using an explicit allowlist\n\n### Migration\n\nAfter upgrading, if client-side code needs access to specific environment variables:\n\n**Option 1: Use the `SHAKAPACKER_PUBLIC_` prefix (recommended)**\n```bash\n# Variables with this prefix are automatically exposed\nexport SHAKAPACKER_PUBLIC_API_URL=\"https://api.example.com\"\n```\n\n**Option 2: Use `SHAKAPACKER_ENV_VARS`**\n```bash\nSHAKAPACKER_ENV_VARS=API_URL,FEATURE_FLAG bundle exec rails assets:precompile\n```\n\n### Action Required\n\nAfter upgrading, **rotate any secrets** that may have been exposed in previously compiled JavaScript bundles.\n\n### Resources\n\n- Fix PR: https://github.com/shakacode/shakapacker/pull/857",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "shakapacker"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.5.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "shakapacker"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.5.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/shakacode/shakapacker/security/advisories/GHSA-96qw-h329-v5rg"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/shakacode/shakapacker/pull/857"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/shakacode/shakapacker/commit/3e06781b18383c5c2857ed3a722f7b91bdc1bc0e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/shakacode/shakapacker"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-08T21:13:37Z",
    "nvd_published_at" : null
  }
}