codeql-queries

Overview

Per docs.github.com/code-security/codeql-cli:

CodeQL is GitHub's semantic-analysis SAST. The model differs from pattern-based scanners (Semgrep / SonarQube):

1. Build a database representing the codebase as queryable facts (control flow, data flow, type info).
2. Run queries (.ql files) against the database to surface findings.
3. Output SARIF for GitHub Code Scanning integration.

This database-then-query model enables cross-file taint tracking (e.g., "any user input that flows to a SQL query without sanitization") that pattern matchers can't express.

When to use

• The team uses GitHub-hosted repos (Code Scanning is GitHub-native).
• The codebase has cross-file taint flows that pattern-matchers miss (e.g., user input → service A → service B → SQL).
• A security audit requires CodeQL coverage (some compliance regimes prefer it).
• The team writes custom queries for org-specific patterns.

For multi-platform CI without GitHub, use semgrep-rules or sonarqube-rules.

Step 1 - Install

CodeQL CLI download from github.com/github/codeql-cli-binaries/releases. Per cql-docs the CLI is bundled separately from the queries - install both:

# Download CodeQL CLI (per platform)
curl -L https://github.com/github/codeql-cli-binaries/releases/latest/download/codeql-linux64.zip -o codeql.zip
unzip codeql.zip
export PATH="$PATH:$PWD/codeql"

# Verify
codeql --version

Query packs (the .ql files) are pulled per-scan via --download flag or pre-installed via codeql pack download.

Step 2 - Create a database

# For interpreted languages (JS, Python, Ruby): no build needed
codeql database create my-db --language=javascript --source-root=.

# For compiled languages (Java, C#, Go): wrap the build
codeql database create my-db --language=java --command="./gradlew build" --source-root=.

codeql database create my-db --language=cpp --command="make all"

The --language flag accepts: cpp / csharp / go / java / javascript / python / ruby / swift / kotlin (verify support against cql-docs for the current CodeQL release).

For JS/TS + Python, the --build-mode none extraction works without a build step. For Java/C#/C++, you MUST wrap the project's build via --command so CodeQL can observe compilation.

Step 3 - Analyze with query packs

codeql database analyze my-db \
  --format=sarif-latest \
  --output=results.sarif \
  codeql/javascript-queries

Common query packs (per cql-docs):

Each pack ships query suites: code-scanning (default for GitHub Code Scanning), security-and-quality (broader), security-extended (more rules, more false positives).

codeql database analyze my-db \
  codeql/javascript-queries:codeql-suites/javascript-security-extended.qls \
  --format=sarif-latest \
  --output=results.sarif

Step 4 - Custom query authoring

/**
 * @name Hardcoded JWT secret in jwt.sign call
 * @description Detects jwt.sign() calls with literal-string secret
 * @kind problem
 * @problem.severity error
 * @id js/hardcoded-jwt-secret
 * @tags security
 *       external/cwe/cwe-798
 */

import javascript

from CallExpr call, StringLiteral secret
where
  call.getCalleeName() = "sign" and
  call.getReceiver().(VarRef).getName() = "jwt" and
  call.getArgument(1) = secret
select call, "Hardcoded JWT secret detected: " + secret.getValue()

The CodeQL query language has a steeper learning curve than YAML patterns (Semgrep). Worth the investment for cross-file taint flows; overkill for simple "find this token" rules.

Custom queries register in a query suite (.qls) for selective execution.

Step 5 - False-positive triage (MANDATORY)

Three layers:

Justification template (mandatory in code):

// codeql[js/sql-injection]
// Reason: parameter pre-validated via Joi schema (line 42); literal interpolation safe
// Reviewer: alice@example.com (2026-05-15)
// Expires: 2026-12-15
const result = await db.query(`SELECT * FROM users WHERE id = ${userId}`);

GitHub Security tab dismissals are persistent + auditable + show in the audit log; prefer them over inline comments for production suppressions.

Cadence: every quarter, review GitHub Security → "Dismissed alerts" filter; expired ones reopened for re-review.

Step 6 - CI integration

Most teams use the GitHub-hosted action (recommended for any GitHub-hosted repo):

jobs:
  codeql:
    runs-on: ubuntu-latest
    permissions:
      security-events: write   # for SARIF upload to Security tab
    steps:
      - uses: actions/checkout@v5
      - uses: github/codeql-action/init@v3
        with:
          languages: javascript, python
          queries: security-extended
      - run: ./gradlew build   # or whatever build step is needed
      - uses: github/codeql-action/analyze@v3
        with:
          category: "/language:javascript"

For non-GitHub CI (GitLab / Jenkins), use the CodeQL CLI directly (Steps 2 - 3) and upload SARIF to GitHub Code Scanning via the API or to a SARIF-compatible viewer.

Step 7 - Database performance

CodeQL databases can be GBs for large codebases. Performance flags:

codeql database create my-db --language=java \
  --command="./gradlew build" \
  --threads=8 \
  --ram=8192   # MB

For incremental scanning (changed-files-only), GitHub's hosted runner uses caching across runs. Self-hosted CI must implement caching manually (the codeql-action/init action handles it on GitHub).

Anti-patterns

Limitations

• Database creation is slow for large codebases (10 - 30 min on monorepos); incremental scanning helps but requires caching.
• Custom-query learning curve is steep (CodeQL is a declarative logic language; CodeQL University courses recommended).
• Some languages have less depth than others (Go, Ruby, Swift are newer than JS/Java/C++).
• Self-hosted (non-GitHub) integration requires manual SARIF routing.
• License: CodeQL CLI is free for open-source repos; commercial use requires GitHub Advanced Security license.

References

• cql-docs - CodeQL CLI getting started
• codeql.github.com/docs - official documentation root
• codeql.github.com/codeql-standard-libraries/ - per-language stdlibs
• github.com/github/codeql - query packs source
• learningqltest.github.io/learningql/ - CodeQL University training
• semgrep-rules, sonarqube-rules, bandit-python, gosec-go - sister scanners
• sast-finding-triager - unifier agent