What Claude Code’s Security Guidance Plugin Does
Claude Code’s Security Guidance Plugin is an AI-powered secure coding tool that performs real-time vulnerability detection on in-progress code, reviewing changes for risky patterns, common flaws, and deeper logic issues while developers write and refine software. Instead of waiting for static analysis scans or late-stage pull request checks, the plugin runs during active development sessions and automatically examines both human-written and AI-generated code. Anthropic designed the plugin to flag injection flaws, unsafe deserialization, insecure DOM APIs, and weak cryptographic patterns before changes enter formal review. According to Anthropic, the plugin “serves as a lightweight first pass, catching issues before a full code review,” which positions it as a complement rather than a replacement for traditional security processes. This workflow aims to reduce security debt, shrink the backlog of comments on pull requests, and keep developers focused inside their editors instead of juggling separate security tools.
Three-Stage AI Code Review Built Into the Workflow
The Security Guidance Plugin integrates three review stages directly into the Claude Code workflow, covering everything from quick pattern checks to deeper AI code review passes. The first stage runs on file edits using lightweight pattern matching without calling a model, scanning for dangerous constructs such as eval(), new Function(), os.system(), child_process.exec(), unsafe deserialization methods, and browser injection patterns tied to dangerouslySetInnerHTML or .innerHTML. After each model turn, a second stage examines the entire git diff to uncover issues that simple patterns might miss, including authorization bypasses, insecure direct object references, injection flaws, server-side request forgery, and weak cryptography. A third, deeper review kicks in when Claude commits or pushes via its Bash tool, reading surrounding files, sanitizers, and related code paths to validate findings and reduce false positives. Together, these layers provide continuous feedback without forcing developers to switch tools.
Reducing Security Debt Without Context Switching
By embedding vulnerability detection into the same session where code is written, Claude Code security checks aim to shrink security debt before it forms. Developers no longer have to trigger a separate scanner or wait for security teams to flag issues in pull requests. Instead, problems surface in real time, alongside code suggestions, so fixes can be applied while the context is still fresh. According to Anthropic, internal rollout data showed “a 30–40% decrease in security-related comments on PRs opened using the plugin,” indicating fewer issues escape into later review stages. The plugin’s ability to scan AI-generated diffs after each model turn also helps ensure that suggested code does not introduce subtle authorization or injection flaws. For teams under pressure to ship, this means fewer late surprises, shorter review cycles, and a more predictable path to cleaner, production-ready code.
Customization, Governance, and Enterprise Alignment
Beyond default checks, the Security Guidance Plugin supports custom rules so organizations can align Claude Code security behavior with their own standards. All three review layers can be extended with repository-specific policies, and teams can define rules in a claude-security-guidance.md file placed in the repo or distributed via MDM. Once present, the plugin enforces these organization-specific requirements alongside its built-in vulnerability detection. The tool is free across all Claude Code plans, with instant pattern checks running without model calls, while deeper reviews draw from the same usage budget as standard Claude requests. It requires Claude Code version 2.1.144 or later and Python 3.8 or newer, and its deeper stages depend on running inside git repositories. By baking security and compliance features into the core editor experience, Anthropic signals a broader push to make secure coding tools a default part of AI code assistance rather than an optional add-on.