The secure container that Lightning Web Components (LWC) run in to prevent security vulnerabilities is called "Locker Service."

Locker Service:

Purpose: Locker Service is a security architecture provided by Salesforce to enhance the security of Lightning components, including LWC.

Isolation: It isolates components in their own namespace, preventing direct access to the DOM and ensuring that components cannot interfere with each other.

Prevention of Security Vulnerabilities: Locker Service mitigates common security vulnerabilities such as cross-site scripting (XSS) attacks by preventing unsafe DOM access.

Strict Rules: Components running in the secure container must adhere to strict rules and policies defined by Locker Service, ensuring a secure runtime environment.

Cross-Origin Access Control: Locker Service controls access to the DOM across different origins, enhancing security by preventing unauthorized access to sensitive information.

Key Features of Locker Service:

Namespace Isolation: Components operate in their own namespace, reducing the risk of naming conflicts and unintended interactions.

Secure DOM Access: Components have access only to a secure subset of the DOM, preventing unauthorized manipulation of the document.

Content Security Policy (CSP): Locker Service enforces CSP rules to control the loading of external scripts and resources, enhancing protection against injection attacks.

Restrictions on External Libraries: Locker Service imposes restrictions on the use of third-party JavaScript libraries to ensure compatibility and security.