Best practices for securing credentials in MCP servers

In 2026, securing credentials on Model Context Protocol (MCP) servers is crucial as many developers still rely on outdated security practices, like using plaintext files or hardcoding credentials, which makes them vulnerable to attacks. Best practices to enhance security include replacing .env files with runtime secret injection, implementing least privilege with per-server credentials, automating credential rotation, using OAuth 2.1 for client authentication, and enabling comprehensive audit logging. Additionally, secure deployment patterns, such as separating secrets across environments and verifying MCP server integrity, are essential to prevent unauthorized access and mitigate security risks. Implementing these strategies can protect sensitive information and ensure that MCP servers are robust against potential threats, with tools like Doppler offering crucial support for runtime injection and secrets management.