# Cwe 94 Code Injection

> Use this skill when you need to remediate CWE-94 (Code Injection) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing code injection issues.

- Skill: `developerscoffee/cwe-94-code-injection` (Agent Skill)
- Install (CLI): `npx skillmds@latest add developerscoffee/cwe-94-code-injection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/developerscoffee/cwe-94-code-injection/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-94-code-injection

---


# CWE-94 Code Injection

## Description

Code Injection

Reference:
https://cwe.mitre.org/data/definitions/94.html


**OWASP Category**: A03:2021 – Injection


---

## Vulnerable Pattern


### ❌ Example 1: Vulnerable Pattern

```java
// VULNERABLE: User input executed as code
ScriptEngine engine = new ScriptEngineManager().getEngineByName("JavaScript");
engine.eval(userScript);
```


**Why it's vulnerable:** This pattern is vulnerable to Code Injection




---

## Deterministic Fix


### ✅ Secure Implementation: Secure Implementation

```java
// SECURE: Avoid dynamic code execution
// Use predefined operations instead of user-provided scripts
Map<String, BiFunction<Object, Object, Object>> operations = Map.of(
    "add", (a, b) -> ((Number)a).doubleValue() + ((Number)b).doubleValue()
);
if (operations.containsKey(userOperation)) {
    return operations.get(userOperation).apply(a, b);
}
```


**Why it's secure:** Implements proper protection against Code Injection




---

## Detection Pattern

Look for these patterns in your codebase:


```bash
# Find ScriptEngine eval
grep -rn "ScriptEngine.*eval\\|engine.eval" --include="*.java"
```



---

## Remediation Steps


1. Never execute user-provided code directly

2. Use whitelisted operations/functions instead of dynamic scripts

3. If scripting is required, use sandboxed environments


---

## Key Imports

```java

import java.util.function.BiFunction;

```

---

## 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-94 vulnerability
Resolve Code Injection issue
Secure this Java code against code injection
SAST reports CWE-94
```

---

## Common Vulnerable Locations

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

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

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

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


---

## References


- [CWE-94: Code Injection](https://cwe.mitre.org/data/definitions/94.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