Which organization publishes a report of the top 10 most widely exploited web application vulnerabilities?

The organization that publishes a report of the top 10 most widely exploited web application vulnerabilities is OWASP (Open Web Application Security Project).

OWASP is an open community dedicated to enabling organizations to develop, purchase, and maintain applications and APIs that can be trusted. Their OWASP Top 10 list is a standard awareness document for developers and web application security that represents a broad consensus about the most critical security risks to web applications. The list is updated periodically as new trends in vulnerabilities are identified and as the landscape of web application security evolves.