PT-2026-3410 · Rubygems · Shakapacker

Published

2026-01-08

·

Updated

2026-01-08

CVSS v3.1

7.5

High

VectorAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Summary

Since 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.
This is not a regression - the vulnerable code has existed since the original Webpacker implementation. No recent code change in Shakapacker triggered this issue.

Impact

Any 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:
  • DATABASE URL - Database credentials
  • AWS SECRET ACCESS KEY - AWS credentials
  • RAILS MASTER KEY - Rails encrypted credentials key
  • STRIPE SECRET KEY, TWILIO AUTH TOKEN - Third-party API keys
  • Any other secrets present in the build environment
Severity: Critical - secrets are exposed in publicly accessible JavaScript files.

Root Cause

The original code used:
javascript
new webpack.EnvironmentPlugin(process.env)
This makes every environment variable available for substitution. If any code references process.env.SECRET KEY, that value is embedded in the bundle.

Patches

Upgrade to version 9.5.0 or later, which uses an allowlist approach that only exposes NODE ENV, RAILS ENV, and WEBPACK SERVE by default.

Workarounds

If developers cannot upgrade immediately:
  1. Audit client-side code and dependencies for any process.env.X references to sensitive variables
  2. Remove sensitive variables from the build environment
  3. Override the default plugins with a custom webpack/rspack config using an explicit allowlist

Migration

After upgrading, if client-side code needs access to specific environment variables:
Option 1: Use the SHAKAPACKER PUBLIC prefix (recommended)
bash
# Variables with this prefix are automatically exposed
export SHAKAPACKER PUBLIC API URL="https://api.example.com"
Option 2: Use SHAKAPACKER ENV VARS
bash
SHAKAPACKER ENV VARS=API URL,FEATURE FLAG bundle exec rails assets:precompile

Action Required

After upgrading, rotate any secrets that may have been exposed in previously compiled JavaScript bundles.

Resources

Fix

Information Disclosure

Found an issue in the description? Have something to add? Feel free to write us 👾
dbugs@ptsecurity.com

Weakness Enumeration

CWE-200

Related Identifiers

GHSA-96QW-H329-V5RG

Affected Products

Shakapacker