cwe-501-trust-boundary-violation

name	cwe-501-trust-boundary-violation
description	Use this skill when you need to remediate CWE-501 (Trust Boundary Violation) vulnerabilities in Java code. Triggers on SAST findings, security reviews, or when fixing trust boundary violation issues.
version	1.0.0
license	MIT
tags	["security","java","cwe-501","remediation","sast"]

CWE-501 Trust Boundary Violation

Description

Trust Boundary Violation

Reference: https://cwe.mitre.org/data/definitions/501.html

OWASP Category: A04:2021 – Insecure Design

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Vulnerable Pattern

❌ Example 1: Vulnerable Pattern

// VULNERABLE: Storing unvalidated data in session
String role = request.getParameter("role");
session.setAttribute("userRole", role);  // Attacker can set role=admin!

// VULNERABLE: User object stored without validation
User user = deserializeUser(request.getInputStream());
session.setAttribute("currentUser", user);  // Unvalidated!

Why it's vulnerable: This pattern is vulnerable to Trust Boundary Violation

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Deterministic Fix

✅ Secure Implementation: Secure Implementation

// SECURE: Validate before storing in session
String role = request.getParameter("role");

// Validate against allowed values
Set<String> allowedRoles = Set.of("user", "viewer", "editor");
if (!allowedRoles.contains(role)) {
    throw new SecurityException("Invalid role: " + role);
}
session.setAttribute("userRole", role);

// SECURE: Only store data retrieved from trusted source
// Don't trust client-provided user data - fetch from database
String userId = request.getParameter("userId");
User user = userRepository.findById(userId)
    .orElseThrow(() -> new AuthenticationException("User not found"));

// Verify user is authenticated before storing
if (!isAuthenticated(user, request)) {
    throw new AuthenticationException("Not authenticated");
}
session.setAttribute("currentUser", user);

Why it's secure: Implements proper protection against Trust Boundary Violation

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Detection Pattern

Look for these patterns in your codebase:

# Find session.setAttribute with user input
grep -rn "session.setAttribute" --include="*.java" -B5 | grep "getParameter"

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Remediation Steps

1. Never store unvalidated user input in session

2. Validate data against allowlist before trusting

3. Fetch user data from database, not from client

4. Authenticate/authorize before promoting to session

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Key Imports

import javax.servlet.http.HttpSession;

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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

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Trigger Examples

Fix CWE-501 vulnerability
Resolve Trust Boundary Violation issue
Secure this Java code against trust boundary violation
SAST reports CWE-501

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Common Vulnerable Locations

Layer	Files	Patterns

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

| Service | *Service.java | Business logic |

| Repository | *Repository.java | Data access |

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References

• CWE-501: Trust Boundary Violation

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Source: Generated by Java CWE Security Skills Generator Last Updated: 2026-03-07