Yagcioglutoprak

Legacy Actions artifact uploads store the `Content-Encoding` header without validation in the column used as the `Content-Type` during download. If the value starts with `video/` or `audio/`, the sandboxing Content-Security-Policy (a security layer that helps detect and mitigate certain types of attacks, including Cross-Site Scripting) is removed. This allows a user capable of running an Actions job to upload an artifact that a browser renders as HTML when the direct download URL is accessed. On public repositories, these URLs are reachable anonymously. A victim opening the link executes the attacker's script within their own session, which could grant an attacker full control of the instance if the victim is an administrator.

Repository and organization project boards failed to verify if a viewer had the necessary permissions to read pull requests that referenced issues on the board. This allowed users, including anonymous visitors of public boards, to see the path of a private repository, as well as the number, title, and state of private pull requests. The pull request body, diff, and files remained protected.