cwe-820-unsynchronized-access

Remediate CWE-820 missing synchronization vulnerabilities in Java code.

3|1|Updated Mar 6, 2026
One-click install
npx skills add https://github.com/DevelopersCoffee/java-cwe-security-skills --skill cwe-820-unsynchronized-access
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: cwe-820-unsynchronized-access
Source: https://github.com/DevelopersCoffee/java-cwe-security-skills/tree/main/cwe-820-unsynchronized-access
Command: npx skills add https://github.com/DevelopersCoffee/java-cwe-security-skills --skill cwe-820-unsynchronized-access

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill addresses critical security vulnerabilities in Java applications arising from missing synchronization, preventing race conditions and ensuring thread-safe access to shared resources.

Core Features & Use Cases

  • Vulnerability Identification: Detects patterns of unsynchronized access to shared mutable state, non-thread-safe collections, and complex multi-threaded operations.
  • Deterministic Remediation: Provides precise, secure code implementations using AtomicInteger, ConcurrentHashMap, and synchronized blocks to enforce thread safety.
  • Use Case: When a SAST tool flags a CWE-820 vulnerability in a multi-threaded Java service, this Skill can be used to automatically refactor the affected code to use thread-safe constructs, mitigating potential data corruption or application crashes.

Quick Start

Use the cwe-820-unsynchronized-access skill to secure the provided Java code snippet against missing synchronization issues.

Frequently Asked Questions about cwe-820-unsynchronized-access

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I fix CWE-820 missing synchronization vulnerabilities in Java multi-threaded applications?

To fix CWE-820 missing synchronization vulnerabilities in Java, you remediate unsynchronized access to shared mutable state by applying thread-safe programming patterns like AtomicInteger, ConcurrentHashMap, and synchronized blocks to prevent race conditions.

What is unsynchronized access to shared mutable state in Java concurrency?

Unsynchronized access to shared mutable state in Java occurs when multiple threads concurrently read or write non-thread-safe collections without deterministic synchronization, causing data corruption and race conditions.

How do I make non-thread-safe collections thread-safe in Java?

You make non-thread-safe collections thread-safe in Java by refactoring unsynchronized code to use deterministic thread-safe constructs like ConcurrentHashMap, ensuring data integrity and application stability during concurrent multi-threaded operations.

When do I need to use synchronized blocks for shared resources in Java?

You need to use synchronized blocks for shared resources in Java when a SAST tool flags CWE-820 vulnerabilities involving complex multi-threaded operations, requiring deterministic code transformations to enforce thread safety and secure shared mutable state.

Does remediating CWE-820 with AtomicInteger prevent race conditions in Java?

Remediating CWE-820 with AtomicInteger prevents race conditions in Java by replacing unsynchronized shared mutable state with secure, thread-safe code implementations, ensuring data integrity and application stability during concurrent access.

What are the limitations of using synchronized blocks for concurrent access issues in Java?

Limitations of using synchronized blocks for concurrent access issues in Java include potential performance bottlenecks in multi-threaded applications, making alternatives like AtomicInteger or ConcurrentHashMap necessary for deterministic remediation of unsynchronized shared mutable state.