GitHub Secret Scanning not detecting hardcoded API keys in Java String constants

[ersuayrus]

🏷️ Discussion Type

Bug

Body

GitHub Secret Scanning fails to detect API keys and passwords when hardcoded in Java source files as static constants, even with Advanced Security enabled. Secrets in plaintext configuration files (.properties, .env) are detected immediately, but identical secrets in Java source code go unnoticed.

Example of Undetected Secrets (Java Code)
Java
public class AppConfig {
public static final String API_KEY = "sk-XXXXXXXXXXXXXXXXXXXXXXXXXXXX";
public static final String DB_PASSWORD = "mySecretPassword123!";
}
Example of Detected Secrets (Configuration Files)
properties
API_KEY=sk-XXXXXXXXXXXXXXXXXXXXXXXXXXXX
Environment Details
Repository Type: Private (with Advanced Security enabled)
Language: Java 21 + Spring Boot 3.x
Build Tool: Maven
Expected Behavior: Secrets should be detected consistently across all file types
Actual Behavior: Alerts only trigger for .properties and .env files, not .java files

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[suresurya]

This is actually a known limitation. GitHub Secret Scanning primarily targets specific file types and patterns like .env, .properties, .yaml, .json rather than scanning raw Java source code for string literals.

For catching hardcoded secrets inside .java files, here are your options:

1. Use detect-secrets as a pre-commit hook

pip install detect-secrets
detect-secrets scan > .secrets.baseline

This catches secrets in any file type including .java before they even hit the repo.

2. Add Trufflehog to your GitHub Actions workflow

- name: Scan for secrets
  uses: trufflesecurity/trufflehog@main
  with:
    path: ./
    base: main

3. Use SpotBugs with Find Security Bugs in your Maven build

<plugin>
    <groupId>com.github.spotbugs</groupId>
    <artifactId>spotbugs-maven-plugin</artifactId>
    <version>4.8.3.1</version>
</plugin>

But the real fix is to never store secrets in source code at all. Use Spring Boot's @Value annotation instead:

@Value("${API_KEY}")
private String apiKey;

Then inject the actual value through GitHub Actions secrets at runtime. That way the secret never touches your codebase.