# Cwe 606 Unchecked Loop Condition

> Use this skill when you need to remediate CWE-606 (Unchecked Input for Loop Condition) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing unchecked input for loop condition issues.

- Skill: `developerscoffee/cwe-606-unchecked-loop-condition` (Agent Skill)
- Install (CLI): `npx skillmds@latest add developerscoffee/cwe-606-unchecked-loop-condition`
- Raw SKILL.md: https://api.skillmd.com/api/skills/developerscoffee/cwe-606-unchecked-loop-condition/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-606-unchecked-loop-condition

---


# CWE-606 Unchecked Input for Loop Condition

## Description

Unchecked Input for Loop Condition

Reference:
https://cwe.mitre.org/data/definitions/606.html


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


---

## Vulnerable Pattern


### ❌ Example 1: Vulnerable Pattern

```java
// VULNERABLE: User controls loop iterations
int count = Integer.parseInt(request.getParameter("count"));
for (int i = 0; i < count; i++) {
    processItem(i);  // DoS if count is MAX_INT
}

// VULNERABLE: Sleep duration from user
int sleepMs = Integer.parseInt(request.getParameter("delay"));
Thread.sleep(sleepMs);  // DoS if delay is very large
```


**Why it's vulnerable:** This pattern is vulnerable to Unchecked Input for Loop Condition




---

## Deterministic Fix


### ✅ Secure Implementation: Secure Implementation

```java
// SECURE: Enforce maximum limits
private static final int MAX_ITERATIONS = 1000;
private static final int MAX_SLEEP_MS = 5000;

int count = Integer.parseInt(request.getParameter("count"));
if (count < 0 || count > MAX_ITERATIONS) {
    throw new IllegalArgumentException("Count must be 0-" + MAX_ITERATIONS);
}
for (int i = 0; i < count; i++) {
    processItem(i);
}

// For sleep operations
int sleepMs = Integer.parseInt(request.getParameter("delay"));
sleepMs = Math.min(Math.max(sleepMs, 0), MAX_SLEEP_MS);
Thread.sleep(sleepMs);
```


**Why it's secure:** Implements proper protection against Unchecked Input for Loop Condition




---

## Detection Pattern

Look for these patterns in your codebase:


```bash
# Find loops with parsed input
grep -rn "for.*parseInt\|while.*getParameter" --include="*.java"
```


```bash
# Find Thread.sleep with user input
grep -rn "Thread.sleep" --include="*.java" -B5 | grep "getParameter"
```



---

## Remediation Steps


1. Define MAX constant for all user-controlled loops

2. Validate input is within acceptable range

3. Use Math.min() to cap values at maximum

4. Log attempts to exceed limits for monitoring


---

## Key Imports

```java

```

---

## 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-606 vulnerability
Resolve Unchecked Input for Loop Condition issue
Secure this Java code against unchecked input for loop condition
SAST reports CWE-606
```

---

## Common Vulnerable Locations

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

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

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

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


---

## References


- [CWE-606: Unchecked Loop Condition](https://cwe.mitre.org/data/definitions/606.html)


---

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