Cline Security Best Practices
Built your app with Cline? Open-source coding agents move fast. Make sure they didn't skip security along the way.
Verify your app follows these best practices automatically.
These best practices are derived from the actual security findings we see in Cline apps — not a generic OWASP list. Priority ordered: critical items close data-exposure gaps, high items prevent compromise, medium items reduce attack surface. Stack-specific guidance for Supabase included.
Quick Wins
Security Best Practices
#1Unrestricted System Access
mediumCline runs commands directly in your terminal. In auto-approve mode, it can install packages and modify configs without human review.
Implementation
Scan your deployed application with a security tool that understands this stack. Address the specific findings — generic best practices don't catch platform-specific misconfigurations.
#2Context-Leaked Secrets
highCline reads your project files for context. If code contains API keys, the agent may propagate them into new files.
Implementation
Move all secrets server-side (environment variables, serverless functions). Rotate any keys previously in frontend code. Audit bundles for leftover credentials before each deploy.
#3Close: Missing Database Security
criticalWhen Cline creates database schemas, RLS policies and access controls are often omitted.
Implementation
Enable Row Level Security (Supabase) or Security Rules (Firebase) on every table. For custom backends, enforce authorization at the query layer — never client-side.
#4Insecure Dependency Installation
highCline installs npm packages autonomously. Without review, it may install outdated or compromised packages.
Implementation
Run `npm audit` on every install. Verify suggested packages exist and have an established reputation before installing. Pin versions for reproducible builds.
Common Mistakes to Avoid
Unrestricted System Access
Cline runs commands directly in your terminal. In auto-approve mode, it can install packages and modify configs without human review.
Scan your deployed application with a security tool that understands this stack. Address the specific findings — generic best practices don't catch platform-specific misconfigurations.
Context-Leaked Secrets
Cline reads your project files for context. If code contains API keys, the agent may propagate them into new files.
Move all secrets server-side (environment variables, serverless functions). Rotate any keys previously in frontend code. Audit bundles for leftover credentials before each deploy.
Missing Database Security
When Cline creates database schemas, RLS policies and access controls are often omitted.
Enable Row Level Security (Supabase) or Security Rules (Firebase) on every table. For custom backends, enforce authorization at the query layer — never client-side.
Insecure Dependency Installation
Cline installs npm packages autonomously. Without review, it may install outdated or compromised packages.
Run `npm audit` on every install. Verify suggested packages exist and have an established reputation before installing. Pin versions for reproducible builds.
Verify Your Cline App Security
Following best practices is the first step. Verify your app is actually secure with a comprehensive security scan.
Get Starter ScanFrequently Asked Questions
What's the minimum security I need for a Cline app?
The critical-priority items above are non-negotiable for any Cline app that handles user data: close: missing database security. Everything else is iterative.
Should I run a security scan before launching a Cline app?
Yes — unconditionally. The mitigations above are specific enough that a scan proves they're implemented correctly. "I followed the checklist" isn't evidence; "the scan came back clean" is.
Is Cline secure by default?
Cline provides secure infrastructure, but the application-layer configuration (listed above) is the developer's job. The default state of a Cline app before any security work typically has at least one critical-priority issue open.
Related Cline Security Resources
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More on Cline Security
Every angle of Cline security — from the specific findings we detect to step-by-step fixes.
Cline Security Scanner
Hub page: scan your Cline app for vulnerabilities.
Cline Security Risks
Specific risks we find in Cline apps, with real-world examples.
Cline Security Issues
Issues grouped by severity with detection and fix steps.
Cline Security Checklist
Pre-launch checklist covering every finding class for Cline.
How to Secure Cline Apps
Step-by-step hardening guide for Cline deployments.
Last updated: April 2026