CVE-2021-38384: 
JavaScript vulnerability analysis and mitigation

Serverless Offline version 8.0.0 contains a vulnerability where it incorrectly returns a 403 HTTP status code for routes with a trailing slash character when using custom authorizers. This behavior differs from the actual Amazon AWS environment, which returns a 200 HTTP status code for the same requests (GitHub Issue).

The vulnerability occurs in the authorization handling of API routes. When a route is defined with a trailing slash and protected by a custom authorizer, Serverless Offline 8.0.0 incorrectly evaluates the authorization policy, resulting in false negative access denials. The issue has been assigned a CVSS v3.1 base score of 9.8 CRITICAL with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability could lead to developers implementing incorrect access control mechanisms based on the false behavior observed in local testing. This discrepancy between local and production environments might result in security controls that are either too permissive or too restrictive, potentially leading to unauthorized access in production environments (NVD).

Developers should be aware of this behavioral difference when testing API authorization locally. It is recommended to test authorization policies both locally and in a deployed AWS environment to ensure correct access control implementation (GitHub Issue).