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CWE-526: Information Exposure Through Environment Variables

Overview

This guidance helps you interpret and remediate findings from DAST (Dynamic Application Security Testing) tools. The scanner detected that sensitive information from environment variables was exposed in HTTP responses. Evidence includes error pages or debug endpoints revealing environment variable contents, stack traces showing secrets, or responses containing process.env, $ENV, or os.environ values. Application responses inadvertently disclose credentials, API keys, or configuration from the environment.

Analyzing the Dynamic Scan Result

What the DAST Scanner Found

DAST findings for CWE-526 typically indicate that values originating from environment variables were exposed at runtime, such as:

  • Environment variables included in error messages or stack traces
  • Debug or diagnostic endpoints returning environment configuration
  • Application responses containing secrets derived from environment variables
  • Process or container metadata endpoints exposing environment values

Evidence is based on observed runtime output, not on request parameters or payloads.

Mapping DAST Findings to Source Code

CWE-526 does not map to a specific request parameter or endpoint. The issue resides in how environment variables are accessed and surfaced at runtime.

When tracing this issue in code, look for:

  • Access to environment variables containing secrets or sensitive data
  • Logging or error handling that outputs environment values
  • Debug or diagnostic features that dump configuration or process state
  • Framework defaults that expose environment information in errors

Remediation

Core Principle: Never allow environment variable values containing sensitive information to be exposed through application output, errors, logs, or diagnostics; access to such data must remain confined to trusted execution contexts.

Verification and Follow-Up Testing

After applying the fix:

1. Verify Runtime Output

  • Trigger error and edge conditions and confirm environment variables are not exposed
  • Review logs and diagnostic output for leaked configuration values

2. Test Debug and Diagnostic Features

  • Validate that debug endpoints or metadata APIs do not return environment values
  • Confirm production configurations disable verbose output

Re-run DAST Scanner

Re-run the dynamic scanner to confirm environment-derived values are no longer observed in responses.

Additional Resources