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jabrenajabrena/cursor-rules-java/skills/124-java-secure-coding/SKILL.md

124-java-secure-coding

Skill452 starsChanged 3 months agoApache-2.0View on GitHub

Use when you need to apply Java secure coding best practices — including validating untrusted inputs, defending against injection attacks with parameterized queries, minimizing attack surface via least privilege, applying strong cryptographic algorithms, handling exceptions securely without exposing sensitive data, managing secrets at runtime, avoiding unsafe deserialization, and encoding output to prevent XSS. This should trigger for requests such as Review Java code for secure coding; Find input validation risks in Java code; Review Java code for injection vulnerabilities; Improve secure error handling in Java services; Harden Java code against common security flaws. Part of Plinth Toolkit

We split this skill into the rules it gives an agent

8 rules. About 0 are common, 3 are distinctive, and 5 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈3

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 5

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Before applying any secure coding changes, ensure the project compiles.

    line 28
  2. Very specific:

    MANDATORY: Run ./mvnw compile or mvn compile before applying any changes

    line 30
  3. Distinctive:

    SAFETY: If compilation fails, stop immediately — do not proceed until the project is in a valid state

    line 31
  4. Very specific:

    VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements

    line 32
  5. Distinctive:

    BEFORE APPLYING: Read the reference for detailed good/bad examples, constraints, and safeguards for each secure coding pattern

    line 33
  6. Very specific:

    Run ./mvnw compile or mvn compile and stop immediately if compilation fails.

    line 47
  7. Very specific:

    Read references/124-java-secure-coding.md and identify applicable vulnerabilities and hardening opportunities.

    line 51
  8. Very specific:

    Run ./mvnw clean verify or mvn clean verify after applying improvements.

    line 59

≈ “Common” is an estimate: at least 1 in 5 of the 308,232 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Java Secure coding guidelines

Identify and apply Java secure coding practices to reduce vulnerabilities, protect sensitive data, and harden application behaviour against common attack vectors.

What is covered in this Skill?

  • Input validation: type, length, format, and range checks
  • SQL/OS/LDAP injection defence via PreparedStatement and parameterized APIs
  • Attack surface minimisation: least-privilege permissions, removal of unused features
  • Strong cryptography: BCrypt/Argon2 for passwords, AES-GCM for encryption, digital signatures; avoid deprecated ciphers (MD5, SHA-1, DES)
  • Secure exception handling: log diagnostic details internally, expose only generic messages to clients
  • Secrets management: load credentials from environment variables or secret managers — never hardcoded
  • Safe deserialization: strict allow-lists, prefer explicit DTOs over native Java serialization
  • Output encoding to prevent XSS in rendered content

Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.

Constraints

Before applying any secure coding changes, ensure the project compiles. If compilation fails, stop immediately — do not proceed until resolved. After applying improvements, run full verification.

  • MANDATORY: Run ./mvnw compile or mvn compile before applying any changes
  • SAFETY: If compilation fails, stop immediately — do not proceed until the project is in a valid state
  • VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements
  • BEFORE APPLYING: Read the reference for detailed good/bad examples, constraints, and safeguards for each secure coding pattern

When to use this skill

  • Review Java code for secure coding
  • Find input validation risks in Java code
  • Review Java code for injection vulnerabilities
  • Improve secure error handling in Java services
  • Harden Java code against common security flaws

Workflow

  1. Compile project before secure-coding changes

Run ./mvnw compile or mvn compile and stop immediately if compilation fails.

  1. Read secure-coding reference and assess risks

Read references/124-java-secure-coding.md and identify applicable vulnerabilities and hardening opportunities.

  1. Apply secure-coding improvements

Implement selected protections for input validation, crypto, secrets, deserialization, and output encoding.

  1. Verify with full build

Run ./mvnw clean verify or mvn clean verify after applying improvements.

Reference

For detailed guidance, examples, and constraints, see references/124-java-secure-coding.md.

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