The query_one() method throughout the Textual documentation allows users to retrieve a single widget that matches a CSS selector or a widget type. You can pass in up to two parameters to query_one(), which are the CSS selector and the widget type, or both at the same time.
Google credits security researcher Shaheen Fazim with reporting the exploit to Google. The dude's LinkedIn says he's a professional bug hunter, and I'd say he deserves the highest possible bug bounty for finding something that a government agency is saying "in CSS in Google Chrome before 145.0.7632.75 allowed a remote attacker to execute arbitrary code inside a sandbox via a crafted HTML page."
The Microsoft Defender team says that the attacker created fake web app projects built with Next.js and disguised them as coding projects to share with developers during job interviews or technical assessments. The researchers initially identified a repository hosted on the Bitbucket cloud-based Git-based code hosting and collaboration service. However, they discovered multiple repositories that shared code structure, loader logic, and naming patterns.