The dependency review feature in GitHub Advanced Security is implemented via the dependency-review-action. This action is primarily designed to run on the pullrequest event. This allows it to scan for dependency changes and vulnerabilities introduced in a pull request before they are merged into the main branch, displaying results directly in the pull request's "Files Changed" tab.

The action can also be triggered manually using the workflowdispatch event. This provides the flexibility to run a dependency scan on-demand against any branch, outside of the standard pull request lifecycle, for auditing or specific security checks.

C. trigger is a generic term and not a valid event keyword used in the on: section of a GitHub Actions workflow file.

D. commit is not a valid event keyword for triggering a GitHub Actions workflow. The correct event for commits being pushed to a repository is push.

1. GitHub Docs, "Configuring dependency review": The official documentation provides an example workflow that explicitly uses on: pullrequest to trigger the dependency review action.

Reference: See the "Example workflow" section.

URL: https://docs.github.com/en/code-security/supply-chain-security/understanding-your-software-supply-chain/configuring-dependency-review

2. GitHub Docs, "Events that trigger workflows": This document lists all valid events for GitHub Actions. It confirms that pullrequest and workflowdispatch are valid events, while trigger and commit are not.

Reference: The list of events on the page.

URL: https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows

3. GitHub Marketplace, "Dependency Review Action": The official page for the action states, "This action scans your pull requests for dependency changes and will fail if it finds any vulnerable dependencies." This highlights pullrequest as the primary trigger.

Reference: Main description paragraph.

URL: https://github.com/marketplace/actions/dependency-review

When GitHub Dependabot identifies a vulnerable dependency in a repository where alerts are enabled, it initiates a standard, automated workflow. First, it generates a Dependabot alert, which is a formal record of the vulnerability. This alert is then made visible within the repository's "Security" tab, providing a centralized location for maintainers to review and manage security issues. Concurrently, assuming default notification settings are in place, GitHub automatically sends notifications to users with admin permissions for the repository, ensuring that those responsible for security are promptly informed and can take action.

C. This option describes the default enablement state for repositories, not the action taken when a vulnerability is found. Also, alerts are not enabled by default for all private repositories; this requires enabling GitHub Advanced Security.

D. The process is automated against the GitHub Advisory Database. There is no real-time consultation or a new, thorough review conducted for each individual alert generated.

1. GitHub Docs, "About Dependabot alerts." This document states, "When your code depends on a package that has a security vulnerability, we'll generate a Dependabot alert and you can see it on the Security tab of the repository." This directly supports option A.

2. GitHub Docs, "Configuring notifications for Dependabot alerts." Under the section "About notifications for Dependabot alerts," the documentation specifies, "By default, we notify people with admin permissions in the affected repositories..." This directly supports option B.

3. GitHub Docs, "About the GitHub Advisory Database." This page explains that Dependabot uses the GitHub Advisory Database as its source for vulnerabilities, which refutes the idea of a real-time consultation as suggested in option D.

4. GitHub Docs, "Quickstart for Dependabot alerts." This guide confirms that for private repositories, you must "enable the dependency graph and Dependabot alerts for your repository," which contradicts the claim in option C that it is on by default for all private repositories.

When a pull request introduces a dependency that triggers a Dependabot alert, it signifies a known vulnerability. The primary security principle is to prevent this vulnerability from being merged into the main codebase. The correct procedure is to update the dependency to a secure version within the feature branch itself. This action resolves the security risk before the code is integrated, aligning with the "shift left" security practice of addressing vulnerabilities early in the development lifecycle. Merging the pull request without this update would knowingly introduce a security flaw into the default branch.

A. Disable Dependabot alerts for all repositories owned by your organization: This action ignores the identified risk and weakens the overall security posture of the organization, leaving all repositories vulnerable.

B. Fork the branch and deploy the new fork: Forking the branch does not resolve the underlying vulnerability. Deploying code with a known vulnerability is insecure and counterproductive.

D. Deploy the code to your default branch: This is equivalent to merging the pull request with the known vulnerability, which directly contradicts the purpose of security scanning and introduces risk.

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1. GitHub Docs, "About Dependabot security updates." This document explains that Dependabot's purpose is to fix vulnerable dependencies. It states, "Dependabot security updates make it easier for you to fix vulnerable dependencies in your repository. If you enable this feature, when a Dependabot alert is raised for a vulnerable dependency in the dependency graph of your repository, Dependabot automatically tries to fix it by creating a pull request." This supports the principle of updating dependencies as the primary remediation step.

Source: GitHub Docs, Code security > Dependabot > Dependabot security updates > "About Dependabot security updates."

2. GitHub Docs, "About dependency review." This document describes how dependency review works on pull requests to prevent vulnerabilities from being introduced. It states, "Dependency review helps you understand dependency changes and the security impact of these changes at every pull request... you can prevent vulnerable dependencies from being added to your project." This directly supports resolving the issue within the pull request (Option C) before merging.

Source: GitHub Docs, Code security > Supply chain security > Understanding your software supply chain > "About dependency review."

3. GitHub Docs, "Viewing and updating vulnerable dependencies in your repository." This guide details the process for handling alerts, emphasizing that the resolution involves updating the package. It notes, "When you're ready to update the dependency... you can click the Dependabot alert to open the pull request that Dependabot has created to fix the vulnerability." This reinforces that the correct action is to update the dependency.

Source: GitHub Docs, Code security > Dependabot > Dependabot alerts > "Viewing and updating vulnerable dependencies in your repository."

The most complete method involves two key stages. First, GitHub scans the repository's manifest and lock files (e.g., package-lock.json, pom.xml) to generate a dependency graph. This graph maps out all direct and transitive dependencies for the project. Second, Dependabot cross-references every dependency in this graph against the comprehensive list of known vulnerabilities cataloged in the GitHub Advisory Database. When a match is found between a dependency in the graph and a known vulnerability, a Dependabot alert is generated.

A. Dependabot reviews manifest files in the repository: This is only the initial step. Reviewing manifest files is how the dependency graph is built, but it does not, by itself, identify any vulnerabilities.

B. CodeQL analyzes the code and raises vulnerabilities in third-party dependencies: This is incorrect. CodeQL is a static analysis engine for finding vulnerabilities in your own source code, not for checking third-party libraries against a database of known CVEs.

D. The build tool finds the vulnerable dependencies and calls the Dependabot API: This reverses the workflow. The process is initiated and managed within GitHub; it is not dependent on an external build tool detecting a vulnerability and then calling an API.

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1. GitHub Docs, "About Dependabot alerts": This document explicitly states the process: "When GitHub detects a vulnerability from the GitHub Advisory Database, we find every repository that uses the affected version of the dependency and we send a Dependabot alert. We generate Dependabot alerts when: A new vulnerability is added to the GitHub Advisory Database... The dependency graph for one of your repositories changes..." This confirms the use of both the dependency graph and the Advisory Database.

Source: GitHub Docs, "About security alerts for vulnerable dependencies", Section: "How Dependabot alerts are generated".

2. GitHub Docs, "About the dependency graph": This page details how the graph is generated and its purpose. "The dependency graph is a summary of the manifest and lock files stored in a repository... GitHub uses the dependency graph to identify repositories that use a vulnerable dependency when a new security advisory is published." This supports the first part of the correct answer.

Source: GitHub Docs, "About the dependency graph", Introduction.

3. GitHub Docs, "Browsing security advisories in the GitHub Advisory Database": This resource describes the database that Dependabot uses for comparison. "The GitHub Advisory Database contains a curated list of security vulnerabilities that you can view, search, and filter." This confirms the second part of the correct answer.

Source: GitHub Docs, "Browsing security advisories in the GitHub Advisory Database", Introduction.

Dismissing a code scanning alert is the appropriate action when the alert is not relevant to the security of the production application. A common reason for dismissal is when the flagged code is part of a test suite, documentation, or another non-production context. In such cases, the alert is considered a false positive or an acceptable risk. By dismissing it with a specific reason (e.g., "Used in tests"), teams can clean up their security backlog and focus on alerts that represent genuine vulnerabilities in their deployable codebase.

A. If you fix the code that triggered the alert, the alert will be closed automatically after the branch is rescanned; you do not need to dismiss it manually.

B. Dismissing an alert hides a potential issue and does not serve as a preventative measure against developers introducing new problems.

D. An alert for a production error indicates a real vulnerability that must be addressed and fixed, not dismissed and ignored.

1. GitHub Docs, "Managing code scanning alerts for your repository." This document explicitly lists valid reasons for dismissing an alert. It states, "You may want to dismiss an alert for a reason such as... The code is only used in tests." This directly supports the correct answer (C). It also explains that fixing an alert results in it being automatically closed, which invalidates option A.

Reference Section: "Dismissing or deleting alerts" -> "Dismissing an alert"

2. GitHub Docs, "About code scanning alerts." This page describes the lifecycle of an alert. It clarifies that when code that caused an alert is fixed, the alert's status changes to "Fixed" and it is closed automatically on the next scan. This reinforces why option A is an incorrect action.

Reference Section: "About the status and details of alerts"