# Cwe 209 Error Message Exposure

> Use this skill when you need to remediate CWE-209 (Information Exposure Through Error Message) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing information exposure through error message issues.

- Skill: `developerscoffee/cwe-209-error-message-exposure` (Agent Skill)
- Install (CLI): `npx skillmds@latest add developerscoffee/cwe-209-error-message-exposure`
- Raw SKILL.md: https://api.skillmd.com/api/skills/developerscoffee/cwe-209-error-message-exposure/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- License: MIT
- Author: DevelopersCoffee (https://skillmd.com/u/developerscoffee)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/developerscoffee/cwe-209-error-message-exposure

---


# CWE-209 Information Exposure Through Error Message

## Description

Information Exposure Through Error Message

Reference:
https://cwe.mitre.org/data/definitions/209.html


**OWASP Category**: A09:2021 – Security Logging and Monitoring Failures


---

## Vulnerable Pattern


### ❌ Example 1: Vulnerable Pattern

```java
// VULNERABLE: Exposing internal details
@ExceptionHandler(Exception.class)
public ResponseEntity<String> handleError(Exception e) {
    return ResponseEntity.status(500)
        .body("Error: " + e.getMessage() + "\n" +
              Arrays.toString(e.getStackTrace()));
}

try {
    // database operation
} catch (SQLException e) {
    return "Database error: " + e.getMessage();  // Exposes DB details
}
```


**Why it's vulnerable:** This pattern is vulnerable to Information Exposure Through Error Message




---

## Deterministic Fix


### ✅ Secure Implementation: Secure Implementation

```java
// SECURE: Generic error messages with logged details
@ExceptionHandler(Exception.class)
public ResponseEntity<ErrorResponse> handleError(Exception e) {
    String errorId = UUID.randomUUID().toString();
    logger.error("Error [{}]: {}", errorId, e.getMessage(), e);

    return ResponseEntity.status(500)
        .body(new ErrorResponse(
            "An internal error occurred",
            errorId  // Reference ID for support
        ));
}

try {
    // database operation
} catch (SQLException e) {
    logger.error("Database error", e);
    throw new ServiceException("Unable to process request");
}
```


**Why it's secure:** Implements proper protection against Information Exposure Through Error Message




---

## Detection Pattern

Look for these patterns in your codebase:


```bash
# Find stack trace exposure
grep -rn "getStackTrace\|printStackTrace" --include="*.java" | grep -E "response|return"
```



---

## Remediation Steps


1. Return generic error messages to users

2. Log detailed errors server-side with correlation IDs

3. Configure global exception handlers

4. Remove stack traces from production responses


---

## Key Imports

```java

import org.slf4j.Logger;

```

---

## Verification

After remediation:


- Run SAST scanner to confirm vulnerability is resolved

- Review all instances of the vulnerable pattern

- Add unit tests that verify the secure implementation

- Check for similar patterns in related code


---

## Trigger Examples

```
Fix CWE-209 vulnerability
Resolve Information Exposure Through Error Message issue
Secure this Java code against information exposure through error message
SAST reports CWE-209
```

---

## Common Vulnerable Locations

| Layer | Files | Patterns |
|-------|-------|----------|

| Controller | `*Controller.java` | User input handling |

| Service | `*Service.java` | Business logic |

| Repository | `*Repository.java` | Data access |


---

## References


- [CWE-209: Error Message Exposure](https://cwe.mitre.org/data/definitions/209.html)


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**Source**: Generated by [Java CWE Security Skills Generator](https://github.com/DevelopersCoffee/java-cwe-security-skills)
**Last Updated**: 2026-03-07