A Cloudflare Worker is serverless code that runs at the network edge, close to users, rather than on a traditional origin server. It can inspect requests, change headers, rewrite content, and modify the web response before the browser ever sees it. That makes Workers useful for performance, routing, and automation, but also powerful enough to alter what a site delivers.
In cyber security, that power creates both risk and defense opportunities. If an attacker gains a token or deployment path with enough permission, a Worker can be used to inject scripts, redirect traffic, or quietly transform pages across many downstream sites. Defenders use the same model for filtering, sanitization, and security controls, so Worker permissions, secrets, and route changes should be tightly scoped and audited like sensitive infrastructure.